Can you check to see if any auto restore points have been created and in Configure, check to see how much has been used in comparison to what the space has been set to.
Sometimes your anti virus program or other programs in msconfig/Startup can prevent a manual restore point being created.
To isolate all of those - boot up into Safe Mode with Networking to see if you can manually create the restore point.
If that is successful then restart the computer and go Start - type msconfig and press enter.
Under the Startup tab, note which programs have their boxes checked then click on Disable all.
Try to create another restore point after the restart and if that is successful, then it is one of those Start up items as your AV program will have reinstated itself in the partial clean boot and you will need to re-enable one item at a time - restart and attempt the manual restore point for each item until you get the error message again.
If the restore point fails again, then that will point to your AV program blocking.
If you are unable to create a restore point in either of those modes, open a command prompt as an admin and run a system file check.
If you need this - go Start - type cmd.exe - right click on cmd and select Run as administrator - Accept the UAC and at the prompt type sfc /scannow and press enter.
This will take about 15 mins to run and will give it's report on completion.
If that finds no violations - at the next prompt type chkdsk and press enter.
That will give its report in the text regarding any bad files in the volume, but you are looking to see if it reports anything other than 0 KB Bad sectors.
Let us know what the sfc /scannow and chkdsk report if you need to go that far.
