Ok not really sure why but it works now-
ok so what i did was rip the dvd-r to the xbox hd. Loading that up gives me a dshnoard with many more options e.g. not the the 2 games on the multi but a games, apps, emus etc...- pressing "y" for the options and then selecting "configure"
In skin and misc settings i disabled the internal skins option, and menu cacheing
In Music & sound, Enable Music has a yes entrry similarly with music during video & and random music.
Global music is disabled for me so not sure if that'll cause problems for you- try it with and without. Preview audio has been turned off and i think this may have been the problem- cos before when i went to load the game as it loaded the audio in the wmv would begin to play as the game was loading- now its silent
not really sure why this worked but it seems to work- basically ftp'ed the mxm & mxm_skin .xml files back to the pc and replaced those to in my multi and remade then iso and burned it and it works that way too but i can't access the configuration options when its on a disc ( i guess cos the disc is read only)
Checked in the games saves to see if there was an mxm which needed to be there but couldn't find one- hope fully its sorted for good, but if one of the experts sould shed some light as to why that worked it'd be good to know in the future.