Run sfc /scannow from an elevated command prompt.
Check the Desktop Window Manager service is set to local account. Look at Log On tab. (Use services.msc to get there, from start menu search.)
Also disable the AMD External Event service.
Check Windows event logs for suspicious or related events. Click on the links to bring you to Microsoft pages for possible help.
You probably have some funky software set to start with pc when booting. Look at that too.