Dreambox 800 Clone Problems -

the 800's both genuine & clones generate quit & bit of heat in operation,..more so when a hard disk is fitted, the chinese tend not to use flux in their solder, this can cause dry joints,..heat will cause dry joints to expand & make better contact & this might be why your picking up more HD channels,.. some 800 owners have the opposite problem, their box works fine until it heats up then the solder joints expand & poor contacts are the result.
I don't have a disk fitted so I can't help with that one.