I started getting the following errors on my wife's Windows 7 x64 gaming system. Additionally Slush's pool reports no activity from that miner in about the same amount of time. It's got an ATI/AMD HD 6950 in it I believe. It may have started after a driver upgrade, but I've since tried a couple newer (including the latest beta) driver versions. I keep the drivers updated on my gaming system & HD 7950 (currently running Catalyst 13.3, the latest beta) up to date & haven't had any issues. There aren't any obvious errors or graphics glitches showing up when she does any gaming, so I'm a little suspicious of it being an actual problem with the video card.

Any thoughts? My only remaining thought is uninstall the video drivers & try to figure out what the old one she had been running, then revert to it.

Code:

cgminer version 2.11.4 - Started: [2013-04-17 23:00:31]
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(5s):141.4M (avg):139.7Mh/s | A:0 R:0 HW:14 U:0.0/m WU:1.8/m
ST: 2 SS: 0 NB: 2 LW: 53 GF: 0 RF: 0
Connected to stratum.bitcoin.cz diff 1 with stratum as user Fallon.Ivory
Block: 00487eaf99c94c2b... Diff:8.97M Started: [23:07:57] Best share: 0
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[P]ool management [G]PU management [S]ettings [D]isplay options [Q]uit
GPU 0: 73.0C 2358RPM | 140.8M/140.9Mh/s | A:0 R:0 HW:14 U:0.00/m I: 4
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[2013-04-17 23:04:00] GPU0: invalid nonce - HW error
[2013-04-17 23:04:06] GPU0: invalid nonce - HW error
[2013-04-17 23:04:07] GPU0: invalid nonce - HW error
[2013-04-17 23:05:31] GPU0: invalid nonce - HW error
[2013-04-17 23:06:02] GPU0: invalid nonce - HW error
[2013-04-17 23:06:15] GPU0: invalid nonce - HW error
[2013-04-17 23:07:07] GPU0: invalid nonce - HW error
[2013-04-17 23:07:31] GPU0: invalid nonce - HW error
[2013-04-17 23:07:37] GPU0: invalid nonce - HW error
[2013-04-17 23:07:57] LONGPOLL from pool 2 detected new block
[2013-04-17 23:08:07] GPU0: invalid nonce - HW error
[2013-04-17 23:08:13] Stratum from pool 0 requested work restart
[2013-04-17 23:08:24] GPU0: invalid nonce - HW error

I just rationalized getting a new HD 7950 for gaming with bitcoin mining. I've had an old Nivdia 285 that I had running fine with CGminer, albeit relatively slowly. Now that I got my new ATI card online I can get either the ATI ("gpu-platform" : "1") or the old Nvidia running with CGminer, but can't get it to run both. Do I have to launch separate instances of CGminer with different configs & gpu-platform settings, or is there a way to run both via the same instance?

If I have to run 2 instances, would I have to create 2 workers for the pool I'm currently in or can I just use the same worker login for both instances?