First, just to make me happy, please download the McAfee Stinger tool from the link below and once downloaded restart into Safe Mode and run it.

McAfee Stinger Removal Tool

If everything comes up clean, then please change the Virtual Memory settings like this:

Open the Control Panel, then double click on the "System" icon. Once that opens, click on the "Advanced" tab, then click on the 'Settings' button in the "Performance" section. Once that opens, click on the "Advanced" tab again, then the "Change" button in the "Virtual Memory" section. When that opens, make sure that the C drive is highlighted at the top of the screen, then place a dot/tick in the box next to "System Managed Size", then click on OK, Apply, OK, etc.

Next, try shutting down some of the unnecessary start up programs and services on the computer using the instructions in the links below:

For Windows 2000/XP, ignore the first couple of sentences about checking "resources" in the link below but follow the rest of the procedures including the "Services" links at the bottom. Shut down as many unnecessary programs and services as possible.

How To Shut Down Unnecessary Start Up Programs

After following all the procedures above, run Error Checking/Chkdsk and Defrag to optimize the hard drive:

How To Run 'Error Checking/Chkdsk' On Win2000/XP

If none of this helps, then you may have a problem with your RAM. It could be faulty and it needs to be tested.

Hope this helps.