That sounds bad. Did you do anything different with it?
A few possible causes come into mind. Lets identify shall we?
First of all check your hard drive to see if there is something wrong. A lot of programs can help you do this,
here is a list of some popular ones.
This is a very easy tutorial using the standard tool, though I have to warn you it may not cover each and every problem. If your Harddrive is broken - it's relatively cheap to replace but of essence you do so quickly and move over any important files. A system restore will NOT repair a faulty hard drive. Merely hide the symptoms.
The second that springs into mind is a rather mean piece of malware. I recommend
Malwarebytes Anti-Malware to deal with that. It's free and it is extremely powerful. AVG is very popular - but not as powerful when it comes to viruses that actually harm your computers performance and ability.
Please keep us updated on the results. A system restore is not always a proper solution - some viruses learned to sneak their way through them and if you have a hardware problem the symptoms of it are your best friend and should not be removed so you silently lose all your data one day. Consider it a last resort for when you can't figure out how to properly fix it anymore.
Good luck buddy!