there is a pinned thread called error submitting ticket in this section that would cover your issue, to save you looking it up heres a link:
http://navyfield.com/Community/Forum/View.aspx?num=3163&searchtype=0&pagecount=0&searchvalue=&sort=5&category=E01&page1=1
also a forum search would have found other threads pointing you in that direction.
you also can get the error if your trying to attach some large files or non supported extentions.