A little over a week ago I had figured out how to do this. I have Windows 10 with Sonar Home Studio, and I would open the MIDI file first, then import an audio file into that and was able to play the audio and the MIDI at the same time in Sonar.
 
I had to be out of town for a week, and when I tried doing this exact same thing this morning, the audio would play but the MIDI would not.
 
I tried opening the MIDI file in Sonar and it played fine, but as soon as I imported the audio file, the MIDI stopped playing.
 
I hope somebody out there knows how to remedy this. I have tried several things.
 
Here is the error message I get:
Can not open registry. {C25C3D7B-0FBC-4dbb-BA9F-3A7DDEE3818D}
 
I click the "close" button on that, and then I get the following error message:
Failed to insert soft synth.
The synth may not be properly installed.


Thank you in advance for your help!
 
 

Try other MIDI-playing stuff that is very simple.  Maybe use the very simplest soft-synth in your DAW package.  Which one are you using, an add-on that you bought? 

I'm using the TTS-1 (or whatever that's called — I'm not in front of my computer at the moment).
 
It's the Sonar choice that somebody on this forum suggested to me.

Okay, here's what I've got this set to:
 
------------------------------------------------------
 
Audio Setup

Input Device    None
Output Device    Speakers (Realtek High Definition Audio) 1/2

Advanced
Driver Mode    WASAPI Exclusive
Sample Rate    44100
Bit Depth    16

MIDI Setup
Inputs    Outputs
Midisport 2x2 In B    Microsoft GS Wavetable

Soft Synth    General MIDI    Cakewalk TTS-1
 
------------------------------------------------------
 
The bizarre part is that all this was working a week ago before I had to leave town.
 
Thanks again for any help you're able to offer!

First remove the MS Wavetable from the output, leave your MIDI output set to none. 
This allows Sonar to automatically insert TTS-1 when you OPEN a MIDI file. Always open MIDI files. 
You would choose the MIDI Sport as output if you wish to use an outboard synth for playback.  
 
Check your track outputs both midi and audio and make sure they are going to the correct place.
The midi track output will be the TTS-1 or which ever synth you wish to use. 
the audio track will go to your sound card or a Master buss if you have inserted one. 

Well, actually, I tried everything you guys told me here and it still didn't work, so I did an uninstall and a clean reinstall and now it works like a champ. Bizarre.
 
One thing that I had done was that I had loaded the Bose SoundTouch 10 software (app) on my computer, and that sucker usurped ownership of all my sound files (well, as many as it could hijack). I took that off first, and when that didn't work I did the reinstall of Sonar HS and all is well.
 
So, as usual, thank you guys for all your help and for being willing to help an old fossil like me.