Dave Smith Instruments SYNTHESIZERS

hi,
this is kind of off topic since its not an evolver specific issue but
i've got a clock sync problem thats been bothering me for years.
im bringing it up here today since i was just trying to sync the
evolver to cubase SL and thought perhaps some of you gurus
may know the answer.

here's the problem...
when i've got my evolver synced to my sequencer's clock, the
bpm display on the evolver jumps around some. for example, 
if i've got cubase SL transmitting at 120, the evolver will jump
around between 119, 120, and 121.

also, when i start cubase's sequencer, the evolver will first go
to 101 and then jump up into the 119-120 range.

this problem evidences its self with all my other clock syncable
gear too. the degree of instability in the clock sync varries
depedning on the equiptment in question...with my korg kaoss 2
being the most stable to my fizmo's sync being the most unstable.

for an external sequencer sync, the problem is usually not too
noticeable since it usually jumps around in the right range closely
enough and the jumps are very fast. but for synced delays, its a
nightmare because (depending on the sync implimentation) i either
get clicks or massive pitch glitches.

i've had this problem with other sequencers too so i know
its not just a cubase problem. i've also experianced this with 
3 different midi interfaces and on two OS's (XP and 98).

here are my current specs:
win XP
cubase SL
motu midi express XT (parallel)
echo layla 20 (im using the midi on this too)

anyone have any idea what the hell is causing this and how to
fix it?

thanks,
-ugo