Updates causing checkdisk to run??

Hi

I have a new PC, 3 days old, running Windows XP SP2, it was running without
problems.
This morning I ran Update and downloaded all software and security updates
and one hardware update for my monitor.

Now when I reboot, soft or hard, chkdsk is run following a message
"One of your disks needs to be checked for consistency"

Has anyone any idea of what has happened?
I see another similar post but it does not stipulate update as being a
factor.

thanks

Daniel