Symptom

When you use the Tasklist.exe utility included in Windows XP Professional, the following error may be displayed:

ERROR: Class not registered

Resolution

This error might occur if Windows Management Instrumentation (WMI) components are missing or not registered correctly. Registering the WMI components ought to resolve the problem:

The .DLL and .EXE files used by WMI are located in %windir%\system32\wbem. You might need to re-register all the .DLL and .EXE files in this directory. If you are running a 64-bit system you might also need to check for .DLLs and .EXE files in %windir%\sysWOW64\wbem.

To re-register the WMI components, run the following commands at the command prompt:

cd /d %windir%\system32\wbem
for %i in (*.dll) do RegSvr32 -s %i
for %i in (*.exe) do %i /RegServer

Restart Windows. If that does not help, you may try repairing the WMI using the comprehensive rebuild method provided in article Repairing and re-registering the WMI.