I would run a disc error check.
Open windows Explorer and right-click on your system disc.
Choose "properties" and then the "Tools" tab.
Under "Error Checking" click "Check now" and tick both option boxes.
You willget a message saying the disc is in use and offering to do the check when you restart - agree.
Next time you start your computer it will warn you it is about to start a disc check and offer you an opt out (just in case you're too busy to wait).
Your system disc will be thoroughly checked and any "iffy" sectors will be replaced.
Discs have spare sectors so that, if a sector starts to become difficult to read/write it can be replaced by a spare.
This process can take a while, depending on the size of disc, but worth doing if you think there might be problems. No guarantee it will fix your problem but is completely harmless and cannot possibly make the system worse.