This may be some server security setting resetting the post data when they exceed a specific number, please check with your host admin or check the server log.
Here are the logs :
[Thu Sep 25 01:35:04 2014] [error] [client 10.0.55.86] [host proto.snipf.org] (9)Bad file descriptor: failed to stat mapfile, referer: http://proto.snipf.org/administrator/index.php?option=com_jce&view=profiles
[Thu Sep 25 03:15:19 2014] [error] [client 78.246.237.245] [host domain.tld] (104)Connection reset by peer: FastCGI: comm with server "/xxx/xxx/www/recette/administrator/index.php" aborted: read failed, referer: http://domain.tld/administrator/index.php?option=com_chronoforms5&act=edit&id=1
[Thu Sep 25 03:15:19 2014] [error] [client 78.246.237.245] [host domain.tld] FastCGI: incomplete headers (0 bytes) received from server "/xxx/xxx/www/recette/administrator/index.php", referer: http://domain.tld/administrator/index.php?option=com_chronoforms5&act=edit&id=1
[Thu Sep 25 03:15:19 2014] [error] [client 78.246.237.245] [host domain.tld] FastCGI: An error happend on Fastcgi processing, fallback to CGI, referer: http://domain.tld/administrator/index.php?option=com_chronoforms5&act=edit&id=1
[Thu Sep 25 03:15:53 2014] [error] [client 78.246.237.245] [host domain.tld] (104)Connection reset by peer: FastCGI: comm with server "/xxx/xxx/www/recette/administrator/index.php" aborted: read failed, referer: http://domain.tld/administrator/index.php?option=com_chronoforms5&act=edit&id=1
[Thu Sep 25 03:15:53 2014] [error] [client 78.246.237.245] [host domain.tld] FastCGI: incomplete headers (0 bytes) received from server "/xxx/xxx/www/recette/administrator/index.php", referer: http://domain.tld/administrator/index.php?option=com_chronoforms5&act=edit&id=1
[Thu Sep 25 03:15:53 2014] [error] [client 78.246.237.245] [host domain.tld] FastCGI: An error happend on Fastcgi processing, fallback to CGI, referer: http://domain.tld/administrator/index.php?option=com_chronoforms5&act=edit&id=1
and the second part is :
xx.xx.xx.xx domain.tld - [25/Sep/2014:03:15:02 +0200] "GET /administrator/index.php?option=com_chronoforms5&cont=installer HTTP/1.1" 302 26 "http://domain.tld/administrator/index.php?option=com_installer" "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/37.0.2062.120 Safari/537.36"
xx.xx.xx.xx domain.tld - [25/Sep/2014:03:15:03 +0200] "GET /administrator/index.php?option=com_chronoforms5 HTTP/1.1" 200 6977 "http://domain.tld/administrator/index.php?option=com_installer" "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/37.0.2062.120 Safari/537.36"
xx.xx.xx.xx domain.tld - [25/Sep/2014:03:15:03 +0200] "GET /libraries/cegcore/assets/css/datatable/default.css HTTP/1.1" 200 20 "http://domain.tld/administrator/index.php?option=com_chronoforms5" "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/37.0.2062.120 Safari/537.36"
xx.xx.xx.xx domain.tld - [25/Sep/2014:03:15:03 +0200] "GET /libraries/cegcore/assets/css/system_messages.css HTTP/1.1" 200 365 "http://domain.tld/administrator/index.php?option=com_chronoforms5" "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/37.0.2062.120 Safari/537.36"
xx.xx.xx.xx domain.tld - [25/Sep/2014:03:15:03 +0200] "GET /libraries/cegcore/assets/bootstrap/css/bootstrap.css HTTP/1.1" 200 18444 "http://domain.tld/administrator/index.php?option=com_chronoforms5" "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/37.0.2062.120 Safari/537.36"
xx.xx.xx.xx domain.tld - [25/Sep/2014:03:15:03 +0200] "GET /libraries/cegcore/assets/images/enabled.png HTTP/1.1" 200 563 "http://domain.tld/administrator/index.php?option=com_chronoforms5" "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/37.0.2062.120 Safari/537.36"
xx.xx.xx.xx domain.tld - [25/Sep/2014:03:15:03 +0200] "GET /administrator/templates/isis/css/template.css?aba28533fc88e45e314f3921527b84e5 HTTP/1.1" 200 27042 "http://domain.tld/administrator/index.php?option=com_chronoforms5" "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/37.0.2062.120 Safari/537.36"
xx.xx.xx.xx domain.tld - [25/Sep/2014:03:15:03 +0200] "GET /administrator/templates/isis/js/template.js?aba28533fc88e45e314f3921527b84e5 HTTP/1.1" 200 782 "http://domain.tld/administrator/index.php?option=com_chronoforms5" "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/37.0.2062.120 Safari/537.36"
xx.xx.xx.xx domain.tld - [25/Sep/2014:03:15:03 +0200] "GET /administrator/components/com_chronoforms5/chronoforms/assets/images/validate.png HTTP/1.1" 200 1208 "http://domain.tld/administrator/index.php?option=com_chronoforms5" "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/37.0.2062.120 Safari/537.36"
xx.xx.xx.xx domain.tld - [25/Sep/2014:03:15:03 +0200] "GET /administrator/components/com_chronoforms5/chronoforms/assets/images/settings.png HTTP/1.1" 200 1824 "http://domain.tld/administrator/index.php?option=com_chronoforms5" "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/37.0.2062.120 Safari/537.36"
xx.xx.xx.xx domain.tld - [25/Sep/2014:03:15:03 +0200] "GET /administrator/components/com_chronoforms5/chronoforms/assets/images/delete_cache.png HTTP/1.1" 200 1088 "http://domain.tld/administrator/index.php?option=com_chronoforms5" "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/37.0.2062.120 Safari/537.36"
xx.xx.xx.xx domain.tld - [25/Sep/2014:03:15:03 +0200] "GET /administrator/components/com_chronoforms5/chronoforms/assets/images/demos.png HTTP/1.1" 200 1052 "http://domain.tld/administrator/index.php?option=com_chronoforms5" "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/37.0.2062.120 Safari/537.36"
xx.xx.xx.xx domain.tld - [25/Sep/2014:03:15:03 +0200] "GET /administrator/components/com_chronoforms5/chronoforms/assets/images/action.png HTTP/1.1" 200 1412 "http://domain.tld/administrator/index.php?option=com_chronoforms5" "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/37.0.2062.120 Safari/537.36"
xx.xx.xx.xx domain.tld - [25/Sep/2014:03:15:03 +0200] "GET /administrator/components/com_chronoforms5/chronoforms/assets/images/restore.png HTTP/1.1" 200 3730 "http://domain.tld/administrator/index.php?option=com_chronoforms5" "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/37.0.2062.120 Safari/537.36"
xx.xx.xx.xx domain.tld - [25/Sep/2014:03:15:03 +0200] "GET /administrator/components/com_chronoforms5/chronoforms/assets/images/database_table.png HTTP/1.1" 200 1043 "http://domain.tld/administrator/index.php?option=com_chronoforms5" "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/37.0.2062.120 Safari/537.36"
xx.xx.xx.xx domain.tld - [25/Sep/2014:03:15:04 +0200] "GET /administrator/components/com_chronoforms5/chronoforms/assets/images/backup.png HTTP/1.1" 200 4111 "http://domain.tld/administrator/index.php?option=com_chronoforms5" "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/37.0.2062.120 Safari/537.36"
xx.xx.xx.xx domain.tld - [25/Sep/2014:03:15:04 +0200] "GET /libraries/cegcore/assets/images/toolbar/remove.png HTTP/1.1" 200 986 "http://domain.tld/administrator/index.php?option=com_chronoforms5" "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/37.0.2062.120 Safari/537.36"
xx.xx.xx.xx domain.tld - [25/Sep/2014:03:15:04 +0200] "GET /administrator/components/com_chronoforms5/chronoforms/assets/images/copy.png HTTP/1.1" 200 984 "http://domain.tld/administrator/index.php?option=com_chronoforms5" "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/37.0.2062.120 Safari/537.36"
xx.xx.xx.xx domain.tld - [25/Sep/2014:03:15:04 +0200] "GET /libraries/cegcore/assets/images/toolbar/add.png HTTP/1.1" 200 1487 "http://domain.tld/administrator/index.php?option=com_chronoforms5" "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/37.0.2062.120 Safari/537.36"
xx.xx.xx.xx domain.tld - [25/Sep/2014:03:15:09 +0200] "GET /administrator/index.php?option=com_chronoforms5&act=edit&id=1 HTTP/1.1" 200 73813 "http://domain.tld/administrator/index.php?option=com_chronoforms5" "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/37.0.2062.120 Safari/537.36"
xx.xx.xx.xx domain.tld - [25/Sep/2014:03:15:18 +0200] "POST /administrator/index.php?option=com_chronoforms5&act=save&save_act=apply HTTP/1.1" 200 62244 "http://domain.tld/administrator/index.php?option=com_chronoforms5&act=edit&id=1" "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/37.0.2062.120 Safari/537.36"
xx.xx.xx.xx domain.tld - [25/Sep/2014:03:15:20 +0200] "GET /libraries/cegcore/assets/css/system_messages.css HTTP/1.1" 304 - "http://domain.tld/administrator/index.php?option=com_chronoforms5&act=save&save_act=apply" "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/37.0.2062.120 Safari/537.36"
xx.xx.xx.xx domain.tld - [25/Sep/2014:03:15:36 +0200] "GET /administrator/index.php?option=com_chronoforms5 HTTP/1.1" 200 6940 "http://domain.tld/administrator/index.php?option=com_chronoforms5&act=save&save_act=apply" "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/37.0.2062.120 Safari/537.36"
xx.xx.xx.xx domain.tld - [25/Sep/2014:03:15:41 +0200] "GET /administrator/index.php?option=com_chronoforms5&act=edit&id=1 HTTP/1.1" 200 73813 "http://domain.tld/administrator/index.php?option=com_chronoforms5" "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/37.0.2062.120 Safari/537.36"
xx.xx.xx.xx domain.tld - [25/Sep/2014:03:15:52 +0200] "POST /administrator/index.php?option=com_chronoforms5&act=save HTTP/1.1" 200 62244 "http://domain.tld/administrator/index.php?option=com_chronoforms5&act=edit&id=1" "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/37.0.2062.120 Safari/537.36"
xx.xx.xx.xx domain.tld - [25/Sep/2014:03:20:56 +0200] "GET /administrator/index.php HTTP/1.1" 200 6715 "http://domain.tld/administrator/index.php?option=com_chronoforms5&act=save" "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/37.0.2062.120 Safari/537.36"
Hope it helps
Thx for taking time to answer