ERROR: doesnt attach file in ajax session

[angelinux]

Hi, this is my first post I have an error, attaching file.

My Zimbra version is 5 and is in DMZ zone, When I start session and select advanced ajax I can not attach files with any browser, but If I start session from external network (internet) I can attach file without problems.
Internally I have this error when I try to attach files:

method: AjXmlDoc.loadFromString

msg: End Tag 'head' does not match the start tag 'meta'

code: AjxException.INVALID_PARAM
error zimbra.jpg

[angelinux]

Anyone have idea about this error??
The next day, the problem was solved and nobody do anything.

What was the reason??

[mqaroush]

How you solve it??