here you can try to read this link: http://windowsxp.mvps.org/Taskmanager_error.htm or this http://support.microsoft.com/kb/555480 and i hope it will solve your problem more...
Microsoft Windows XP Professional for PC - Troubleshooting
vista will expire after 30 days if not activated so u hav 2 ways one to buy the original key from microsoft or crack the os but its not ethical more...
Microsoft Windows XP Professional for PC - Troubleshooting