Could be a hard drive problem ....
Run the Built in Self-test (BIST) to try and repair your hard drive. To run the hard drive checks, please follow these steps:
* Reboot DVR via red button inside card door.
* When you see "Running receiver self-check" press select
* You will see "Entering Diagnostics Mode..."
* Select Advanced Tests Menu -> Hard Drive utilities -> Short Smart test
You can also run the file test, and the DVR can sometimes repair a bad file report.
* If the other tests pass, run the surface test. Warning: This process could take several hours to complete. You may want to run it overnight.
The good news is that every attempt is made to save programming. This is less destructive than a reformat all and could provide you with a more stable system if you are having problems that appear to be related to the hard drive.