We are experiencing an unusual problem with a few of our users email were they are randomly missing text from the body of a sent email. They will type email hit send but the recipient will receive the email with some or most of the original text missing. The copy of the email in the sent items is also missing the text. It is very random, happens a couple times a week to the affected users. So far 5 out of 50 users have reported this issue. It started happening about 4/5 weeks ago. In the mean time the exchange server has being upgraded from exchange 2003 to exchange 2010 (sbs versions) but not for this reason. It has happened since the upgrade so I suppose that rules out the exchange server. The affected clients are running Office 2003 or Outlook 2003, they have Symantec Endpoint (I have disabled the anti-virus plugin during troubleshooting). Can't seem to find what is common with the PCs having the problem and because of the time between failures its hard to fix.
Any ideas on were to look would be appreciated.