I have a Sony Vaio VGN-NW120J, which recently gave me "Driver irql_less_or_not_equal error" on Windows 7. I have reinstalled the windows since it didn't allow me to run any fixing solution. So do I need to run Windows Memory clean up now because I fear it may give me same error in future. I even installed a new display driver.
Are you on the latest BIOS update for your laptop? That issue seems to be related to your GPU. Are you on the latest GPU drivers? Also, did you modify the innards for the laptop? You can find all your necessary downloads off their support site, here.