That's a "disk check" (also referred to as 'scandisk') which Windows performs on the next re-start whenever it's not been shut down properly. Improper shutdown could either have been done by the user or by a process or application which didn't behave properly.
Don't worry about it unless it happens frequently. It's just Windows making sure you don't have errors before you start using it (Windows says the "volume is dirty" to mean it the drive has errors which it must put right. It can't do this when Windows is running)
Edited by pip22, 03 March 2007 - 12:41 PM.