Analogue-sequencer

I've noticed when my P3 is running after a few minutes it begins to 
stall when it's running an 8-note sequence, it will miss note-8 then 3 
then 5 then 8 again, even if i skip notes it still stalls. I tried 
running a sequence on 12 and 16 and no-change ? 

I'm just wondering if it needs a firmware upgrade or checked out?
The firmware version on it is V3.1.005.

I haven't checked my other P3 for this odd stalling yet....

Regards,
A1k