Adding MSSQL Server Monitor

When trying to add the monitor to multiple servers I receive the the following error.
"80041010 - Specified class is invalid. Try running 'wmiadap /f'(For Windows XP and 2003) or 'winmgmt /resyncperf'(For Windows 2000) command from the monitored device. Refer Troubleshooting Tips"

To which I have followed all of your advice with the exception of restarting the MSSQL Service as these are production servers.
What are the requirments for the credentials that are used to access the wmi information on the server for the MSSQL monitor? Does there have to be any other specific rights assigned beyond the account being an administator of the machine?

Windows Server 2003
MSSQL 2000

Thanks,
Joe