My iSight cam was working just fine untill about a week ago. Now it only works if I do a few things but it dosent even work for that long.

I have to shut down the computer and take out the battery then restart and then the iSight will be found on my system profiler. I then go to skype and chat for a few min and the cam goes away or i get the message that the camera is in use by another program and it stops working. When I check the System Profiler the iSight is not found.

What can I do to fix this problem?? Please help I am in europe for the summer and this is really starting to annoy me.