Jessy just sent this tip over to me this morning:
This is an old issue from about 6 months ago that I encountered this morning. If a user complains about slow opening or Excel or Word files check in Add/Remove Programs (Win7 or XP) for the Office File Validation Add-In update. If its there remove it and reboot. The issue will be resolved. This update causes those files to get stuck over the network when opening.
Jessy Marker