I maintain a set of ME computers at a school and lately 6 of them started
hanging.

The symptom is the same on all of them: if you try to launch Windows
Explorer or the Control Panel, the system hangs. You can Ctrl-Delete and
kill the explorer process to do a bit more work, but it will hang again if
you try to launch Windows Explorer.

If you don't start Explorer you can launch some other applications. I was
able to do both a virus scan and an Adaware scan successfully (didn't find
anything).

Any clue as the cause of this? An suggestion to reset Explorer?

Thanks