Hiya numpty
There's quite a few problems that can cause this. Firstly, make sure you're not running TWO antivirus programs as they always conflict with each other. Have you tried what used to be called ScanDisk. My Computer - right-hand click a hard drive - Properties - Tools tab - Check now - and tick both boxes. Do that for all your hard drives. You could do a hard drive clean-up while you're about it. Then reboot. If this is the problem be prepared for a long wait - I do mine overnight. Connect to www.pcpitstop.com. You'll have to register which is easy and free and let them scan your computer. They'll come back with a report and help you repair any problems. You may also have some software which are conflicting so remove all except those which you really need. Hope this helps.