I too can confirm that DM seems to have compatibility issues with HDs that autosleep. I have a Transcend StoreJet that autosleeps after 10 minutes and for which AFAIK the autosleep can't be disabled--if it can, it might be a per-initialize thing. If I play a game, like say Super Mario Sunshine, the game works fine normally, including saves--this is without nodisc or nmm, btw. But if I'm in an area for a long enough time (say, over 10 minutes), then trying to transition to another area causes problems. Specifically, the game won't be able to detect the memory card (if it's trying to save at that point), the game will give the generic "there was an error" message just like if there were a disc read error, and the HD will spin up. I presume this is an issue in all games, although it probably is a lot less apparent in games that are frequently loading new areas. :/