Windows 2000 constantly freezes

I have a user that uses a dell optiplex GX110. With Win2k as the OS. She is a power user utilizing office 2000. Whenever she has multiple programs open she get s the error message that the program is not responding which causes her machine to freeze up. Rebooting seems to be the only thing do to get around this. She has the power cord of her machine running through a power strip and then to the power outlet. I was thinking it is either the power supply on her pc is going bad or something to with the power strip. Any suggestions for me to look for and try are greatly appreciated. Thanks for any input.

Markus R Bertel