You can press PrtScn on your keyboard - usually just to the right of the F12 key. This copies to clipboard. Then open word or a similar program and paste the image. If you use alt prtscn it will restrict the image to just the active program - useful if you have multiple screens and do not want it all copied.
Funny enough I had the same issue with AH2 towards the end. I had to keep rebooting the game up to 5 or 6 times but it would eventually let me in. I did not bother searching for a solution as AH2 was about to end and I did not have the same problem with AH3.