sync pumping effect

[jacen100]

hi all great to have the forum back up again, i have a problem with sync all i use is the virus ti desktop with cubase and moto 2408mk3 if i have lets say 6 or so tracks pumping from the virus all virus sounds kick drum snares , hats bass and so on, its has a weird effect the timing slowly pretrudes off and on and i get the same effect u get when u would mix to vinyl records the pumping effect were the kick drum dissapears right at the moment everything syncs. even with 2 sounds only a drum and sare i still get it, dont understand why this is happening the sync is terrible my £80 casio syncs better