If the software crashes before you can close after calibration, I'm not sure the calibration has properly been saved and applied.

I have no evidence yet but stability issues and Radeon cards may be related. ALL of my stability issues were traced back to my video card. I spent many hours diagnosing this so I hope you can benefit from this expended effort.

I am now using an Asus GTX 670 Direct CuII 4GB now and I think it is likely the best board for scanning you can find for the price. This scanner is heavy on graphic memory primarily.

Can you scan in free mode?