Hi,
Shut down the notebook. Tap away at the esc key as you start the notebook to enter the Start-up Menu. Select the Diagnostic Menu option ( f2 ) and run tests on both the Hard Drive and Memory. Post back with the details of any error messages.
Can you also post back with the following details.
1. The full Model No. and Product No. of your g6 series notebook - see Here for a guide on locating this information.
2. The full version of the operating system you are using ( ie Windows 8 64bit ).
Regards,
DP-K