MS Outlook problem, possible virus

I'm having this problem on my boss's computer: In his MS Outlook (windows xp) old emails that he has read automatically start becoming "unread" again - they get highlighted and the little number in () beside 'inbox' starts going up and up. Does anyone know how I can solve this? thanks

 

so outlook2002 is just sitting there open on my computer, and im watching the inbox go from:

inbox (288)
inbox (289)
inbox (290)
...
...

and I browse through all the messages in my inbox and I see they are becoming highlighted again as if they are unread.

Also, the send/receive status bar in the bottom corner seems to be working very hard, not the usual 0-100% in a couple seconds.

 

To rule out any malware issues please do the following:

Basic Spyware, Trojan And Virus Removal

Second any unresolved issues in the Spyware Specific Forum

Read the following thread: NO HIJACK THIS LOG FILES BEFORE READING THIS: HJT Tutorial & LOG File Posting