The default limit for MSSQL text fields in php is 4096 bytes which is what is causing the problem when the system tries to get the content back out of the database.
You will need to edit the php.ini on the server and uncomment (by removing the ; in front of the line) and change the settings
; Valid range 0 - 2147483647. Default = 4096.
;mssql.textlimit = 4096
; Valid range 0 - 2147483647. Default = 4096.
;mssql.textsize = 4096
to something more reasonable, for example
; Valid range 0 - 2147483647. Default = 4096.
mssql.textlimit = 131072
; Valid range 0 - 2147483647. Default = 4096.
mssql.textsize = 131072
You may need to restart your web server after making this change for it to take affect.
