Run malwarebytes free version here you may get the option for the trial version un-tick this box.
When you say it wont shut down Does it keep restarting, or just says shutting down on screen and never gets any further than that.
What anti-virus do you have and have you given it thorough run.
you could also run MS File checker see here
Opening command prompt. click Start, Programs, Accessories, right-click Command Prompt, click Run as administrator. If you have a password pop it in if not you will be taken to command promt. Type sfc /scannow and hit enter.
The sfc /scannow scans protected system files, replaces incorrect ones with correct MS files.
All so try a restore go to start, programs, accessories, system tools, and restore, follow the instructions it will give you the best options available.