Sound like you have a corrupt WMP library. Try deleting it and starting fresh. To delete it, delete all the *.wmdb files found under %LocalAppData%MicrosoftMedia Player
You’ll need to stop the WMPNetworkSvc service if you’ve had Media Center running or reboot and then delete before running Media Center.
NET STOP WMPNetworkSvc
DEL /Q “%LocalAppData%MicrosoftMedia Player*.wmdb”
Disclaimer: You’ll lose all your music metadata that isn’t embedded, ratings, played history, etc…nothing I care about but others might.
