Hi Matt & Noel96,

Thanks for your responses.

To Matt - in a weird way, it's good to know that it's not only me with this experience. But of course, it's NOT good. And you read me correctly. The drift isn't an equal drift from start to end. It's perfect snyc to about Bar 35 when it becomes noticeable
and then at around Bar 65 it jumps to being unacceptably noticeable. I'm fairly certain that it is not my imagination running away with me (queue for a song).

To Noel96 - ACID information is totally new to me. Thanks for mentioning it. I will research it and then check within Cakewalk. All I know is that I set BIAB to 129bpm whole units and when in Cakewalk, I also typed in a round 129bpm.
Your 2nd question Noel shows up my ignorance : "are you using a MIDI for the net in Cakewalk as well?". Would you mind explaining this a bit more to me.

Whilst you have both been brave to jump in on this and give me helpful pointers, I hope others will simply advise if they have had the same experience.

All the best
Chris