Midi and Audio Timing in sync then out of sync

This post is regarding problems with both midi and audio:

I’m not sure what is going on with Cubase 5.0 and REWIRE and Reason 5.0

The playback of my Midi notes are sliding off tempo by a noticeable amount.

Heres what going on:

I have a midi bass line starting at measure 25 (The midi notes are triggering an external synth).
Reason 5.0 is running a drum beat in the background 4 on the floor beat.

On 1st pass of the song (e.g. starting point in Cubase 5 Measure 1) I press play and when the sound begins to play at Measure 25 (although notes are quantized the midi notes are noticeably off mark and audiably dragging and lagging behind)
Now here’s the strange part, when I press stop for a moment in Cubase 5 and set up loop markers from Measure 25 – 32 and then press play again the sound is exact and right on nothing lagging and reason sounds fine too, drums perfectly ontime.

Also, just for courisity I decided to create a wave file of that midi Bass I use in my chorus measure 25 >.

On 1st pass of the song (Measure 1 right up to then end of the Chorus) the chorus bass line is off again comparing it to the beat coming in via REWIRE from Reason.
Once again I press stop botton and go maybe to measure 22 and press play and it’s playing back perfectly again….But I cannot get it to play perfectly from the BEGINNING to the end of my chorus without the sound sliding off (and very noticable)

Anyone have an idea what is going on?

Could be that external instruments don’t get delay compensation. Is DC enabled in the project? What if you disable it?

I added in that component “Delay Compensation” and that doesn’t make the slightest difference.

Start up the song let it roll up to my chorus and voila (still out of sync with both midi notes and Audio file.
Back up the song a couple of measures, start the song on say measure 23 and voila the midi and audio is synced perfectly.

Well, my only work around at this moment is this: from my experimentation. I cannot start the song at measure 1 bottom line.
I can start the song at say measure 2 and when it reaches Measure 25 the Chorus, it is all sync. Anything but from the starting point of the song works fine!

hmm… any ideas what is causing this?

Try the System Timestamp option in Cubase. DEVICES > DEVICE SETUP > MIDI>MIDI Port setup and check “Use System Timestamp”. Check out this sos article… http://www.soundonsound.com/sos/dec07/articles/cubasetech_1207.htm