Sounds as if you may have picked up a `nasty`.
I suggest you run your anti-malware software to check for any virus/spyware/trojan/etc. you may have picked up.
Make sure you update prior to running the scans.
If you do find malware you may be wise to turn off Restore, do a Restart, run your anti-malware software again and turn Restore on again.
After cleaning your PC you should create a Restore Point and run Ccleaner or similar to clean up the Registry.
If you still have problems post back.