The easiest solution would be to uninstall and then reinstall your audio and video drivers, but multiple symptoms like you are describing are rarely that easy to fix.
Audio drivers for MX6025:
Video drivers for MX6025:
Gateway Display Drivers Version: 188.8.131.5289
If that doesn't work, then I suggest formatting and reinstalling Windows. It's the only guaranteed way to revert your laptop to a working state (assuming there isn't a hardware issue), and it will save you many headaches. It only takes about 30 minutes to reinstall Windows, and an addition 30 minutes to install all your drivers. Just make sure you burn your drivers to disk before formatting.