Ok guys I ran into the same problem. I tried to cut out two copies of the same image and the machine started cutting wacky. So I hit the kill switch so I wouldn't waste vinyl (started running the whole roll of easy weed).
Needless to say I rebooted CPU and cutter. So all fresh and I send one cut via SignCut Pro. It cuts, try to send a second. NO DICE. Just hangs. says 45+ minutes to do a 5 minute cut.
I tried to kill SignCut pro, reboot, etc, etc. Still only get one cut in. So now with a hung set-up I went to sign cut pro and set the compatability mode to 'windows xp service pack 3' (no reboot) and the cutter starts to work.
That said, I am leaning on a driver issue. Run compatability. It should work.
[edit] I did one cut and it hung again. Killed Sign Cut Pro, and it still did not cut. So Killed Sign Cut Pro and unplugged USB. Started Sign Cut Pro and replugged USB and it cut the vinyl.[edit}