Vista requests run of Chkdsk on boot

Here is my situation and I do not know what is the cause.

In the past week four out of five times when I boot up my Vista
computer after the initial post Vista is invoked. During the boot
process the program wants to run CHKDSK because it says there is some
problem on my c drive. Chkdsk goes through all steps and when done
and reports the status of what it did it reports no bad sectors,
nothing being repaired. Vista then restarts and then goes as though
there were no problems.

The next time I boot up if on the same day it will usually not request
to run chkdsk. However, after the PC has been shut down for a period
and then booted up CHKDSK will then again be run unless I abort the
process.

Can some one please tell me what might be causing this problem and how
to permanently fix it. If you need more information to help me please
respond accordingly.

Thanks,
oldman