Computer freezes/locks when closing open applications (Win 7)???

[Birdman]

Win 7 x64 (tweaked services); 4GB RAM

Start-up programs:

NIS 2011
WinPatrol Plus
Process Lasso
Ad Muncher
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My computer completely locks/freezes randomly whenever I try closing a 3rd-party program application. The mouse pointer still moves, but I'm unable to click on anything on my screen (including start button + taskbar items).

Ctrl-Alt-Del function allows me to open up the 'task manager' but I can not click on any of the tabs. The only way to unlock my computer is to 'Log Off' and log back in.

I've noticed this happening alot whenever I open up my WinPatrol Explorer or Puran Defrag gui and upon closing the applications (red "x" button).......my computer locks and becomes inoperable (besides the mouse).

Does anyone know what might be causing this problem and how to fix it?

I've already ran CHKDSK and defragged my drive. It's driving me insane.

Thanks

[Cudni]

did chkdsk find or fix errors? check event viewer logs for error in case they offer more clues.

[littlebits]

It most likely is caused by Process Lasso, try removing it from your system startup and then reboot.

Add NIS 2011 to Process Lasso exclusion list because the Tamper Protection will probably not work with it.

Thanks.:)

[Birdman]

Chkdsk did not find any errors. I un-installed 'Process Lasso' but I'm almost certain that I started having this issue PRIOR to installing PL.....but we shall see.

Where in the "Event Viewer" should I be looking for any errors that would relate to this?