Hi, MJB.
Lots of computer problems are cleared up by simply rebooting, as you
probably know if you've dealt with PCs for very long. That's why MS set the
default for "what to do on system failure" to "automatically restart". But
when the reboot does not clear up the problem, we are left with no clue as
to what happened.
Go to System Properties | Advanced | Startup and Recovery Settings. Remove
the check from the box that says Automatically restart.
Next time this happens, when you come back you will see a BSOD (Blue Screen
of Death) full of cryptic codes. You'll still have to reboot your computer,
but you'll have plenty of time to read those codes first. If they don't
make sense to you, copy them verbatim and include them in your next post.
Some guru (not me!) will be able to interpret them and point you in the
right direction.
If you still get reboots without the BSOD, the problem is probably in the
hardware (power glitch, bad cables, defective RAM), not in Windows or a
program.
RC