Hi Bendi,
Sorry, but I can’t reproduce it.
I checked it with windows 7 + Cubase 7 for 17 minutes several times with different ext. interfaces during the playback
If we had after 30 sec 0,2 - 0,3 sec sync drifting, we should out off the beat after 17 minutes.
But it isn’t, can not confirmed this report.
Cubasis has an excellent timing with internal/external midi + audio devices.
Please send us an detailed step by step description to repro this issue.
best
jan