I'm running a machine with Windows XP Professional 64-bit. Every so often, it will freeze for no apparent reason. That is, everything stops responding, except the mouse. I can move the mouse around, but I can't click on anything. Keyboard input is also not accepted/received when this problem occurs.

The three-finger salute fails to bring up the Task Manager. Even pressing the power button on my computer fails to shut it down. The only way out of this that I have found is to hard-reboot the machine (i.e. pull power or hold power button in for 10 seconds).

This problem was occurring on the system when it had all its updates and after a fresh install when not everthing was quite yet updated. I've run the Scandisk utility and the latest version Memtest86 that supports 64-bit architecture; neither found any errors.

The last time this happened was on a fresh install of Windows. Only Nero Essentials, Avast antivirus (disabled), Firefox, and Spybot were installed. I was not running Nero, Firefox, or Spybot at the time, and Avast was disabled, so I'm pretty certain this is a Windows issue.

Is anybody familiar with this problem or have any pointers?