Cursor Locks Up Intermittently

Can anyone tell me what I should check to find or fix the problem that is causing my cursor to suddenly freeze on my screen and stop recognizing my mouse or keyboard? I have an AMD processor, 1 GHz; 512 MB RAM, 80 GB hard drive; running Windows XP. I use MS Explorer for my browser and access the internet with a High Speed cable modem. I use ZoneAlarm Pro firewall protection and Norton Corporate AV. The cursor locks up whether or not I have the firewall activated and whether or not I have the AV program activated. I try to keep the Windows Updates current.
It doesn't seem to matter whether I am browsing the internet, working with Outlook Express, or working on my desktop with one of the applications or solitaire games; the cursor will suddenly just stop. Sometimes it will go most of the evening without locking up; other times it will lock up within a few minutes of starting the computer.
When it freezes up, I have to turn my computer off by securing the power, then restart it. Usually, one restart is good for the evening; other times I may have to restart two or three times.

Help! Any suggestions?

Thanks,
Bill

 

Shot in the dark -
Under Display Properties\Troubleshoot if you move the slider for Hardware Acceleration one notch to the left you "disable cursor and bitmap accelerations. Use this setting to correct problems with the mouse pointer or to correct problems with corrupt images ".

 

If you find the answer, I wanna know. I have a similar problem, and I've been replacing hardware systematically, haven't solved it yet. Only thing left for me to change is the hard drive and the CD -RW...Just like you said, the freezes are random and inexplicable. I have no keyboard response either, and often have to reboot several times- cursor is still locked at the log in screen.

 

Thanks Pete C. and Johanna. I've downloaded Memory Diagnostics and the instructions. I'm about to run it now. Thought it best to thank you now just in case I mess up the whole thing and have to run this computer into the shop! I hope I'm just kidding!
Thanks a lot for your responses.
Bill