Since this is, in essence, a new Windows 7 installation, it might need specific updates or drivers installed.
Check for missing or corrupt files using the System File Checker.
Check for any Microsoft Windows 7 update. Note that some MS updates have caused problems; see http://www.forbes.com/sites/jasonevangelho/2014/12/13/new-windows-7-patch-is-effectively-malware-disables-graphics-driver-updates-and-windows-defender/, for example.
Go to the HP support site (e.g. http://support.hp.com/us-en/product/HP-Pavilion-g6-Notebook-PC-series/5048672/model/5078477/drivers/) to get any driver updates for your machine.
Check Device Manager to see if any devices are improperly installed or missing drivers.