Sounds like wuauserv got its knickers in a twist. In order of simplicity, one might delete C : \WINDOWS\SoftwareDistribution\DataStore and reboot. If that doesn't work, delete C : \ WINDOWS\SoftwareDistribution and reboot. Finally, a fix might be to netstop wuauserv, re-register its DLLs and restart it. The details are out there on thar intarweb somewhere.