Could you tell me what version of Windows are you using? The error message you got may have been caused by an outdated driver. Please open Device Manager and check if there is a component that requires attention. I would recommend you to manually update your video driver.
The locked C drive may be a different problem. Are you using the PC as an Administrator? Please run the Command Prompt and type the following command:
chkdsk C: /f /x /r
Wait for the process to end and check again if the partition is accessible. If you have a Windows installation drive, boot from it and select the Repair option. This may fix some errors without harming your data.
Hope this helps