i have similar problem (driver_irql_not_less_or_equal) , my comp resets itself 10-15 times per day. (ı turned off automatically start over option now I get BSODs)
I did not install any new hardware and my virus prg and firewall prg runs on my computer for long time.. (no change)
I changed RAMs.. no effect..
there are no spyware, trojans etc on computer