After some Windows updates were installed the other night, SP stopped working. Tried several things that I found on the 'net, and none worked. Uninstalled and re-installed SP (WSS 3.0) and was able to open our site again. But, I can no longer back it up, this is the error that it's reporting: SqlException: Access to table dbo.backupmediaset is blocked because the signature is not valid. Could not insert a backup or restore history/detail record in the msdb database. This may indicate a problem with the msdb database. How do I fix that?

Hi, It is a problem about WSUS database. Here is similar post (the last answer): http://www.eggheadcafe.com/software/aspnet/33051597/are-you-trying-to-do-a-ma.aspx But you’d better turn to the SQL server form. Hope it is helpful!Seven