Three things:
1. If you look a the Certificates snapin for your 'Local Computer' in MMC and only find a few Trusted Root Certificates then you should run the Microsoft May 2009 Trusted root certificate update from here:
http://www.microsoft.com/downloads/details.aspx?FamilyID=f814ec0e-ee7e-435e-99f8 -20b44d4531b0&displaylang=en
The above fixed the 8192 problem for at least one person that I know of.
As a matter of fact it wouldn't hurt to re-run that whether you think you're missing Ceritificates or not.
2. If you ever had your computer connected to an Active Directory domain then there might be a problem with your Certificate policy. The Local Computer Policy MMC snap-in might show you some settings that you can fiddle with.
This fixed a raft of problems for people to do with updates and sign-ins an so on.
3. Apple now have a support document that points to to an MS knowledgebase article on how to troubleshoot certificate problems on Vista. It's long and involved and the final step if nothing has worked is a reinstall. You should check out the article here:
http://support.microsoft.com/kb/822798
This last one was presented as a solution to problems that were fixed by the first two so try those first.
Best of luck!
Message was edited by: Mike P. Ryan. Typotastic!