Well - thank you - some progress but not quite the complete fix yet.
I purchased the 2012 update via download but it does seem to be the full version.
Didn't realise that so much was left on the system after uninstalling so did exactly as you suggested and went through deleting everything and re-installed from the downloaded file.
Amazingly, the big problem I had with ASIO seems to have been cured (although I hesitate to celebrate too soon) but the problem with CoyoteWT is still there.
It just stopped playing back a few days ago whilst I was using the program.
Just to reiterate, I can get a sound direct from the MIDI instrument and it records. In playback I can see the MIDI notes in the track and the track VU activate but there is no sound when the re-route to default synth box is checked.
I'm not aware that I did anything different. Could it possibly be due to a windows update or something? Would it be worth trying a system restore to a week or so ago? Any further suggestions gratefully received.
Thanks again for the help so far.
Godfrey