Hi All
Thanks to those who have responded.

I did a chat session with a helpful PG tech (Kent) on Friday and was advised that the merge tracks to audio option has always worked this way in PT2010. He could not explain why it had produced a midi track for me recently.

However, he did point me in the direction of another way to do this, and that is to use the Extract Channels To Tracks option under the Edit menu. In this process, you identify the MIDI channels that are to be merged, and send them to an empty track. The only problem I had was that I kept getting no output until I made sure that no channel was being extracted to the track I wanted to use as the destination for the merged tracks. In other words, I wanted to use Track 7 as my destination for Tracks 1-6; Track 1 was on Channel 1, Track 2 was on Channel 2 and so on. In the Extract dialog box, you specify the Track for each Channel, so I extracted Channels 1-6 to Track 7, and made sure that no other channels were going to Track 7 (by default, Channel 7 was going to Track 7, so I just changed it to Track 8. Once I did that, it seemed to work fine. I haven't checked the output closely, but will soon and let the board know if there were any other problems.

I hope this helps someone else.

Barry