No, the error rate isn't affected by whether I close the lid, in either operating system.  In Ubuntu, the only effect of closing the lid seems to be a drop in hash rate (I've never figured out why).  In Windows, the computer always went into hibernation after 15 minutes, even after I disabled hibernation in power management.  I think I've fixed that problem, and I'm hoping that the computer will mine overnight.

I've previously posted here: http://forum.bitcoin.org/index.php?topic=22683.0

but that thread is now much too narrow in scope, so I decided to start a new one.

On Ubuntu, I'm running DiaboMiner and mining for slush.  It's working great, with less than 1% of my blocks being rejected, except for a mysterious problem where the hash rate drops from 70 to 50 Mhash/s after I close the laptop's lid for a while.  However, on Windows, I can't mine without an extremely high error rate.  With DiabloMiner, roughly 40% of my blocks are rejected.  On Phoenix, it's approximately 10%. I've tried ATI Stream v.2.1, v.2.4, Catalyst 10.11, and Catalyst 11.06.  There seems to be no difference in terms of error rate.

Has anybody else encountered the same problem? I'm really hoping that someone has a solution!

I'm having problems with mining on Windows. See this thread: http://forum.bitcoin.org/index.php?topic=22683.0

In addition, DiabloMiner seems to be running a tiny bit (a few percent) faster on Ubuntu than on Windows. I have no idea whether these few percent are statistically significant.

@Stupidpal: Have you tried other mining programs or other operating systems?  If so, have you found a setup that works?  I love Ubuntu, but for some purposes (i.e. astrophotography) there simply isn't enough software written for Linux to make it my sole operating system.  That's why I'd really like to get DiabloMiner working on Windows.

I've been trying to get DiabloMiner working with my ATI Radeon Mobility 5730 card.  On Ubuntu, this works fine, and less than 1% of the blocks found are rejected by the mining pool (slush).  However, with the same SDK and same DiabloMiner version on Windows, roughly 30% of the blocks are being rejected, and 15% return a hardware error.  Has anybody encountered a similar problem before? I use ATI SDK v. 2.1 with Catalyst 10.11.

I also have a different question.  On Ubuntu, my hashrate stays at 70 mhash/s as long as I'm actively using the computer.  When I close the lid--which, according to the power management settings I've set, shouldn't do anything except blank the screen--the hashrate drops to 50 mhash/s. If this expected, and if so, how can I prevent it from happening?