Photoshop CS2 - All tools have stopped working!!

Photoshop CS2 9.0.2 - We have re installed software and run all updates, yet tools are still not working. We can not use brush, clone, eraser, dodge, etc., etc. Could only find a Mac patch for this problem, not Windows. Any advice? We are working on Windows 2000, Dell computer, 521 RAM, 3072 allotted for Virtual Memory.

Reset preferences, and move the stylus that you're not using off the pressure sensitive tablet.

PSCS2 will run in 512MB RAM.

....but it's much happier/faster with a GB or better still, 2GB of good quality RAM.