I appear to have lost the ability to run certain .exe files on my PC, mainly they are setup files or programs designed to run on an older version of Windows. I've tried Compatibility mode but that doesn't help. In all cases, when I look in the Task Manager, I see some thread called "ntvdm", which refers to the ntvdm.exe file in the system32 folder, hogging 100% of the CPU. It doesn't do anything even after leaving it for a few minutes, so I end up having to kill the process otherwise my PC slows down. Anything I need to do to fix this and be able to run these other programs again?