Have you scanned for virus and malware? That's the first thing I'd check if you haven't already. Windows also has a hardware diagnostic tool if memory serves me correctly ( I switched to Mac 3 years ago ) and I'd also run that utility as well. Also, worth checking to see if you've lost RAM....I think there is a Windows utility that will let you know how much RAM is available, and if you've lost RAM the number displayed by this utility will be lower than what is supposed to be installed on your machine.

Could also be a bad driver..printer drivers are sometimes culprits of this type of thing when all of the above comes up ok...If you can recall installing anything new on your computer just before all this started, whatever that installed item may have caused trouble....An update to a Microsoft program like Outlook for example. Just some thoughts, hope it helps!