Typing on left side of 1545 keyboard causes it to go to "sleep"

I am trying my question here as I have not received a response on the Dell laptop forum NOR a phone call back from the $90 Dell support guy who spent over an hour trying to find a virus and update all my drivers (which I had already done).

All of a sudden (a week or so ago), when typing my computer goes to sleep. It is primarily keys on the left side of the keyboard.  I am running Windows 7 over Vista. So I have updated bios, drivers, no virus or malware, any suggestions? Would doing a "clean" install of Windows 7 accomplish anything?

Thanks in advance,

Peggy

(of course in typing this I didn't have any problems.)