System won't Shut Down or Restart

[JSnow]

As of late my pc won't shut down or restart.  It will clear out of desktop and will display the familiar light blue background with a message stating that Windows is shutting down...  But it doesn't.

I have a Gateway PC with Pentium(R) 4 CPU 2.80GHz; 2.79GHz, 1.50 GB of RAM.  Microsoft Windows XP, Home Edition Version 2002, Service Pack 3.  I use Kaspersky Security.

Please let me know if I should post more information about my pc.

added after posted: I just spoke to my wife about this and she said hers is behaving similarly.  We switched to AT&T wireless internest last weekend.  Could that be holding something up?

[Carbon Dudeoxide]

Does Windows shut down in Safe Mode?

[JSnow]

Yes, it shuts down in Safe Mode.  However, I didn't choose Safe Mode w/ networking.

[Carbon Dudeoxide]

All right.

In Safe Mode, I suggest performing a System Restore to a few days before the problem started.