I have a wacom bamboo tablet with a button assigned to Alt. I was drawing something in photoshop, and suddenly that button began switching between tabs in photoshop. It then began switching programs. Finally, it brought up a menu with program icons similar to the Alt+Tab or Windows+Tab menus, but the menu was the classic Windows gray color.

What's worse, it didn't go away. I was able to select programs with my mouse, however I could not open task manager with ctrl+alt+delete or ctrl+alt+escape. Nothing would get the menu off my screen, and I ultimately had to restart the computer. I didn't think at the time to get a screenshot, but does anyone know what this function might have been and how I can make it go away in the future?