have you tried tipping the keyboard upside down and shaking gently?
You would be surprised what comes out,
Other than that, what about keyboard drivers?
This is hard to explain but here it goes. Windows 7 Professional on a new PC Build. Once in a while it acts like the ESC key is being pressed repeatedly because as hover over an application in the task bar,(such as FireFox) it pops up the open windows, but they disappear within a second. This makes it impossible to choose. Also, ALT tab only allows one tab then goes away. ONe time I could not select a folder from a dialog, once again because it seemed ESC was being pressed.
I have to reboot then it's fine, but this has happened about 4 times so far and I don't know why.