Web Cam problems ...

Ok... i have been having a problem with the ability to use my web cam from my mbp on live.yahoo.com. For some reason, i get this stupid error message that says my web cam is in use by another program. So i checked to make sure iMovie and iChat were not opened, and still this error message continued. I then restarted my mbp in hopes that this would fix the problem. Well needless to say, i have been fighting this loosing battle for a week and every thing that i have read doesnt seem to help my problem. If anyone has experience this problem and knows how to fix it, your help would be greatly appreciated.
-Mike