Thats a very general question...
What is your Network topology? Ethernet? 10/100Mbit?
Is your Network connected by Switches or Hubs, or both?
What protocols are you running?
Do you only see the problem in Word/Excel? Since you posted in the GroupWise Forum, do you have application integration turned on in GroupWise?
Sorry for so many questions... just trying to paint the right picture!
Please advise.