For bug-finders:
I have 2 others 290 on windows that did not suffer the bug (except from very rare occasion) but they are watercooled.
Is it possible that the Darkcoin algo make some part of the card too hot, or too something, and that some part of the card are disabled? Again: in scrypt/keccak/Scrypt-jane there is no problem.
VRM temps seem fine:

I wonder if the guys at guru3d would be willing to do a thermal check using their camera for this algo, see if there is any part of that card that overheats.
