Data Execution Prevention

Hi

I've been getting DEP when I open MY COMPUTER or a desktop folder. It happens at least once a day if not more. I can shut down the folder and then reopen it but DEP has been a new occurrence.

I scanned my PC using AVG and Spybot. I also used the Panda online scan but nothing identifiable as a virus/spyware etc came up.

Is it possible to find out what program or file is causing the error?

Suggestions/comments?
Thanks in advance