Computer randomly stops responding, except for...

Nexus Zero

For some reason my computer randomly stops responding to anything other than the Windows key, Ctrl-Alt-Del and mouse movements. For instance, I'll be able to get a run dialogue open with Windows+R, but I won't be able to run anything from it because I can't type. I'll get Task Manager up, but its a frozen window unless I have the Start menu open through the Windows key. The mouse moves around the screen fine, but nothing responds when you hover over, for instance, a button or scroll bar. As shut-down through CAD freezes mid-way, I have to turn the computer off with the power button which I really dislike doing.

I've scanned my computer with fully-updated AVG, Windows Defender and HijackThis, and it comes up clean.

This is probably the strangest thing I've ever had any computer do to me, largely because it seems without a cause. Any suggestions?

redimpulse

Can you boot into safe mode? If so, boot in and check your system and application event logs to see if anything is tossing a process hang. It sounds to me like possibly explorer.exe is faulting.