The graphics drivers for the G41 chipset which launched in 2007 are no longer being developed. The 126.96.36.199.2869 driver is the final driver for the G41 chipset. Have you verified the issue with the latest driver available from the manufacturer of your laptop? It is possible that the manufacturer has customized the driver specifically for you system, especially in areas such as power management, display brightness and backlighting etc.
I also ever tried use driver from the mobo manufacturer but it still got same problem. I think should add a graphic card to solved the problem.