Vista - windows live video and microsoft excel

I have a problem/question,

When I am in the middle of a video call with microsoft live messenger,
if I try to open an excel spread-sheet, it will not open. I don't
think a word document will open either. For some reason, when you do
the video call, it is locking something that it won't allow excel to
open. Any ideas?

I am running windows xp pro, service pack 2,
The windows live messenger is version 2008, build 8.5.1302.1018

I hope this is the correct forum to ask this question on. If not, can
someone tell me which forum I should put it on?

thanks,
ga
George Applegate
gappleg8@xxxxxx