Event ID Errors: 6398, and 6641 on Event Log

If you find out there is still no use for solution on http://support.microsoft.com/?id=946517 and http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=1205873&SiteID=1

Try this:
Central Administration > Application Management > Check Services Enabled in this Farm > Check Services Enabled in this Farm
and see if any service has error on the page.

Then open IIS Manager, Go to Application Pools, check every application pool has wrong access user name and password.