MovieMaker Will NOT Capture, Please Help

I run Windows XPMedia Center w/SP #3 and use Movie Maker 5.1. I've captured
video from my Cannon ZR700 for over a year with no problems but now it won't
capture from the Cannon anymore. The camera shows up in the devices but when
I hit capture in Movie Maker I get "An Unknown Error Has Occurred". It does
rewind the tape but the preview window remains gray. When I try to capture in
Ulead Video Studio 11 it crashes and when I try to capture in ArcSoft ShoBiz
it says the device is unavailable or being used by another program. Device
Manager says the Cannon is working properly with the current driver. As I
said it has worked fine for years until this week. I use this all the time
and I'm lost without it. Can anyone help?
BTW, the capture process works fine when I hook the Cannon up to another
computer using the same Firewire cable and MovieMaker so it's not the camera
or the cable,