Try deleting the contents (not the folder) of c:\windows\prefetch, then
reboot. It will be rebuilt. Prefetch "corruption" can cause slow
program loading.
If you're running Norton Anti-Virus, try disabling Microsoft Office Scan. Go to "options" then "miscellaneous" there you'll see a box regarding scanning Microsoft Office documents...if you disable "office plug in" and click ok, you'll be good to go. Good luck, this worked right away for me.