So I have had this problem where ESC stops working globally while Adobe Photoshop CS3 is open for a few years. CS5 doesn't suffer from this problem, but getting upgrade to CS5 was not easy because CS3 was the version we were using for Space Marine.
So finally I spent some time to find a "fix": it was quite simple.. just open the task manager and kill ccc.exe (it's ATI control panel... so I don't give a shit). Now re-launching CS3 solved the problem. Yay.
Then I ran msconfig from Windows + Run, and then disabled CCC from launching when my machine starts up. If I need to use CCC, I'll manually launch it. I barely use it anyways, so not a big deal.