I have run Win XP Home for several months without a problem. Now, the computer runs fine right after boot, but if you use an application like IE 6.0 for 15-20 minutes, it quits functioning. If you try to launch a program such as Outlook after this time, you may get an error message "Not enough quota is available to process this command". Sometimes you click a taskbar button and nothing happens, no error message, etc. A reboot cures the problem temporarily and then the same problems start again.

I searched this problem on the 'net and found an article suggesting to increase the Virtual Memory paging file size. I increased it from 767 to 1567 (max was already set at 1568) and this immediately made the computer function normally - HOWEVER, after 20 min or so of use, the same problems as above started again! There also was an option to "Let System manage" VM and I tried that, but it didn't help.

I also did all of the above with a diagnostic startup and disabled all the extraneous startup programs I could, but this didn't help.