Emu XL-7 & MP-7 User's Group

Hi
I still working out the XL-7, so this could well be due to me having 
something set funny...
Ive got an 8 bar loop running with 10 tracks running and the kick 
drum which is on track 1 drops out on certain bars even though ive 
checked that the note events are acutally there.
In fact there dosent seem to be a real pattern to the problem as it 
changes postion as to when the notes get dropped. If i mute say 2 of 
the higher tracks (11,12,13) the problem seems to clear up.
Im not over doing the tracks with loads of data either, so i dont 
think its using all the available voices by any means. Theres only 
one track with a bit of controller data going on (filter sweep).
I could understand if an event was trying to trigger the same sound 
twice on another track but that dosent seem to be whats going on.
Also ive noticed that if a change one of the presets for another 
sound that can cure the problem as well (say an arp for example)
Anyone else had this one?

Ps.. would it matter that the first 3 tracks use the same drum kit 
but there on the first 3 midi channels not all set to say channel 1?
 
Regards
Gonz