What you're seeing is autocheck. The system detects a dirty bit on the drive and runs checkdisk at boot. Unfortunately it runs it without any helpful switches, so it will just keep happening until you intercede.
I'm going to assume the check is being done on c: drive. Open a command prompt from within windows and type: chkdsk c: /r (note: there is a space before and after "c:"
Then Press ENTER. You'll be told the disk is in use and asked if you want to run checkdisk at the next boot. Say yes and reboot. Checkdisk will run with the repair switch, so it will take a while depending on the size of your hdd. A couple of things Dave:
1) As is always the recommendation when running any drive level command, make sure you have a current image of your drive "just in case"
2) As I said, checkdisk will take a while because the /r switch tells it to repair both software AND hardware errors (it will move data from bad sectors and mark those sectors unusable in the future). Do not interrupt it - let it finish.
Afterward, your system should boot normally.
