Those errors can be generated by any number of issues. Did the start recently? If so, what is new since before the error started?
Some steps you can take:
1) Download and install the latest video driver. Get it from the ATI website, not from Windows Update
2) Download and run memtest (http://www.memtest.org/
3) Boot to the Recovery Console and run chkdsk /r
Those are the normal first troubleshooting steps for your errors