Check out this Microsoft article. The article doesn't list XP as one of the systems that this applies to, but I found a boatload of entries on google where this was suggested as a fix for an XP machine.
http://support.microsoft.com/default.aspx?scid=kb;en-us;193050
Hi, My task Manager changed. Usually It's three tabs. Tasks, Processes, and CPU. Now it's only one, the tasks. Can someone tell me how to get it back the way it was. I have system restore turned off. Thanks, Herb
Running windows xp home sp2
256 ram
sony vaio desktop

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic