I've been running the Enigma challenge on the same machine as my 7970/Collatz work. Saved 1 thread for the GPU (1 out of 24 including HT) I have a slightly OC'd 7970 that can get through a Large collatz in about 5.2 hours. Last 2 days, they've been hanging on me at 60-ish percent. See pic. I suspended Enigma and started a new task. All the while, my GPU meter reads like it has activity.

I'll be really sad if something is wrong