OK. Since my last post, I have done this:

1) Using Remove Programs - removed every app connected with BIAB, including Coyote and Roland stuff.

2) Deleted all related folders and files, both old install and new. Only exception to this is I put my old compositions into renamed folder on a separate drive, for archive. Also, I checked - with all this deleted it leaves well over 70 Gb of free space on C: partition. My HDs are defragged weekly automatically, but I ran a check, and fragmentation was less than 0.01%.

3) Searched further with google, and located a copy of GM.DLS. Copied it into C:\Windows\System32\Drivers. Updated by hand the registry entry which is supposed to point to this file's location.

4) Then I tried a clean install. Ran the setup program on the 2011 HDD, selected option 3 (everything) and otherwise selected defaults all the way through. On this install, I did not get the "Can't find sound font file GM/DLS" error at end of install or on launch of BIAB, as before.

5) Adjusted Midi/Audio Drivers setup. Load and play any song with Real Tracks or Real Drums parts. Get error message "Beat Map Stretcher was unable to Load in the wav file". If I click through this message, the Real Tracks parts are generated, but Play only produces sound from midi parts (yellow). On most demo songs this is drums and count-in click only, on a few songs there are other midi instruments which play. No real tracks parts (green) or real drum parts produce any sound.

6) Tried John's suggestion next. delete BB and RB folders. Run BIAB from the 2011 HDD. Double checked Setup Midi/Audio Drivers setup. Load demo songs, and try to play. Same error: "Beat Map Stretcher was unable to Load in the wav file". Same play results as above, no real tracks or real drums, but midi works.
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So, to summarize the events so far, here is how I have got to this situation.

1)Had an older version of BIAB running fine for years. Received the 2011 HDD EverythingPAK.

2)Without changing anything on my existing install, I ran the 2011 HDD setup program, selecting the Install everything onto my HDD option, and selected (to the best of my memory) default on file location.

3)First install apparently went to a different directory from existing install, which according to some posters should not necessarily be a problem. Attempts to play produced two errors "Can't find sound font file GM/DLS" on program launch, and "Beat Map Stretcher was unable to Load in the wav file" on play.

4) Made some settings changes in Midi/Audio Drivers Setup (thanks Noel) and got midi to play, but no real tracks.

5) Next, I made one or two attempts like this: remove and, after moving old install files to same location as new install default, re-install. Same errors and lack of real tracks.

6) (as in this post) Attempted to purge my system of all traces of old install, added copy of GM.DLS to drivers folder, and tried running from 2011 HDD. Then tried another install of BIAB, again using everything option, default location. Both of these produces same result. "GM/DLS" error is gone, but "Beat Map Stretcher" error remains and real tracks /real drums parts do not play though midi parts do.

I think the root cause must either a parameter setting in some file somewhere or a entire file in the wrong place or missing somewhere. Thinking logically, since the malfunction is the same now running from 2011 HDD or onboard drive, then the problem is either somewhere in my XP setup, or it is somewhere in the BIAB files so it manifests on both HDD play and installed play.

I really want to avoid having to clean-install my OS just to get my BIAB upgrade to work.

Anybody have any more ideas as to what could be causing the "Beat Map Stretcher" error and lack of realtracks play?

Thanks