Office 2003

When I am on the internet My Office 2003 programs lock up completely if I try to use them. They unfreeze after I leave the internet.
This means no cut & Paste or Powerpoint or excel.
Any ideas How I can solve this???
Athlon 2.2
1.5 Gig
100 Gig
Windows XP Media Center (Curent Servie Packs)
Modem 56k & Netzero
Thank You