cmd.exe window popup

Hi,

Looking for some help for a newbie... I've searched everywhere else & found several old references, but no solution (that I can understand :-( ).

In the last few days the cmd.exe window has started to appear & vanish without any input from me. There's nothing in the window - just blank, black space. I assume there's a virus or trojan or summat else nasty that's gotten in even though McAfee is up to date and always on, and Spybot finds nothing nasty. I've tried restoring to the earliest point available - which predates the symptoms - but it's made no difference.

I did find, somewhere, an error list which suggested that this fault goes back some months, although the symptoms have only been visible the last few days. I can't find the list again - sorry.

Any help will be much appreciated.

PS. Inspiron 530, Vista SP1..