QUOTE(gjm @ Jan 24 2006, 03:49 PM)

In which case HackDaBox's suggestions would still be worth doing as formatting a drive should find bad sectors and mark them as "do not use".. Unless the filesystem on the Xbox hard disk is completely crazy

Of course the Xbox won't mark them so it will use those bad sectrors again. Also bad sectors spread like hell usually, so even those "marked sectors" would not be read, the ones which got damaged since the format will be and there will be a no go again. You really think Xbox will scan your hdd and mark any sector that is damaged under a 5 secs format ? Formatting and bad sector marking will takes some hours in some case (if there are physical bad sectors of course) and that also will not save you from further read errors. Expensive hard drives like SCSI and raid systems can handle BAD SECTORS correctly but drives like you can see in the Xbox do not. (not even if you enable SMART, which I doubt Xbox enables anyway)
As he has nothing to lose of course a format is worth a try, but usually won't help that much on a physically damaged hard drive. To be sure, I'd rather do a backup of my settings/files before the HDD dies totally.
regards, Stephen