jittery midi cursing the darkness in cubase 4

Hi All,

I’m having sloppy/jittery midi problems with cubase 4.5 when using it to control external instruments (roland r8/nord rack). I have had the same set up for years with out an issue, the only thing different is a power mac g5 (2 gig ram, i think its a duel 1.8 processor.)
I dont use Vst’s although i installed a softsynth to see if i could locate the issue, the problem isnt there when using vsts. Adusting the latencty to both extremes does nothing. Something as simple as spitting out one track of 16th notes (cycled) to an external instrument causes great problems.

I’m really stuck and tried everything i can think of, any great minds out there?