Yeah,
I have now encountered the sound going bye-bye and which leads ofcourse to the " please clean your disk etc. " and bumps you back to the dashboard on 3 occasions. played oblivion 30hrs total. Its imo the hard drive demanding every ounce of memeory to make this mammoth run. The 360 has to stream a lot of info from the hdd if i am not mistaken, and these load times, although diminished with the hdd, Still hogs all the hdd's resouces it looks like. I have also tried mid game to delete some existing saves, and man it takes forever to move about the save files let alone delete them. What i think is that the games caches so much info to the hdd that anything involving loading , saving etc, clgs up and frags the hdd which in turn leads to slow performance when loading, etc.
Again, I am sure that Bethesda must have a troll lurking on forums somewhere whom will be passing this info to the poweres that be and hopefully get a damn patch to hopefully fix this issue in general.
Since a lot of this(these) issues are happening, maybe we can get a pin on just the topic itself to see how prevelant this really is amongst Oblivion owners.