Ran into an issue tonight where Windows 7 did not recognize that my Wacom Intuos4 tablet was attached. In fact the tablet didn’t seem to notice it was attached either. The power LED lit, but nothing else showed. I tried updating to the newest driver with no effect. When I went into the Control Panel and tried to open the Wacom Tablet Properties I got a message “Tablet Driver was not Found”
After reading a number of forums that seemed similar issues, I finally found something that fixed it for me. I went into the Devices and Printers and right clicked on the tablet device there. I clicked on Tablet Preference File Utility and then under All User Preferences selected Remove. Immediately the tablet returned to life and I was able to get back to photo editing.
Hope that helps anyone running into a similar issue (or myself if it happens again).