[HKEY_CURRENT_USER \ Software \ Microsoft \ Windows \ CurrentVersion \ Policies \ Explorer]
"NoInstrumentation"=dword:00000001
The user tracking system built into Windows XP is useless to 99% of users (there are very few uses for the information collected other than for a very nosy system admin), and it uses up precious resources to boot, so it makes sense to disable this "feature" of Windows XP. To do so, browse to HKEY_CURRENT_USER \ Software \ Microsoft \ Windows \ CurrentVersion \ Policies \ Explorer and find the DWORD "NoInstrumentation". You may need to create this key if it is not there. The default setting is 0, but setting it to 1 will disable most of the user tracking features of the system.