Strange issue with Messenger and XP

Has anyone ever heard of this???

I have an Exchange 2K server running Messeneger server and 16 WinXP systems, 3 of the 16 are getting a strange issue where instead of going to “Away” after so many minutes the status goes to “Appear Offline”. I’ve unstalled Messenger (including removing the directory and registry setting) and re-install both 4.6 and 4.7 (for XP)

Thinking that this issue was with the Options setting, I turned it off. Still happened, this time after 1 minute even though itwas orginally set for 15.

Any ideas anyone?? This is become a REAL nuisance