Tried everything I can think of to fix this.  My last hope is that one of the knowledgeable members here may be able to help point me in the right direction.

The plug-in is EWQL "Hollywood Strings" using Sonar X3e

Not sure this is a Sonar problem or an Eastwest problem or both but I've tried several times now and can't seem to get any feedback from Eastwest on this.  It's proving to be a tricky problem to nail down on my own

What happens is I insert a new instance of the EWQL Play engine and load up Hollywood Strings.  All seems to go Ok on the initial load.  All inputs/outputs check out, audio is audible, midi tracks/meters showing all normal and OK.  I go ahead and record a midi track.  All ok at this point but sometime shortly after doing this or if I press stop/playback several times or do any more than a few note edits, the audio for that instance of the synth just vanishes as if it had never been loaded.  If I save the project at this point, even a restart of the computer doesn't cure it, (despite the sample appearing to reload normally on opening the project again).  The only way I've found to get the audio on this sample working again is to reload the original sample again from the Play engine browser, (but the same problem loop continues over again from then on).

This is where troubleshooting gets tricky.  My current PC build (Windows 7 x64) is less than a month old.  I have no other issues with sample packs or Sonar.  I reinstalled everything at that time because I invested in a flash system drive and felt that was a good time to refresh everything.  I only mention this because the first thing I did on this new build was to load up a new Sonar test project and inserted one or two instances from each of my Eastwest sample packs to check everything was working, (including of course Hollywood Strings).  And this is where it gets really confusing.  I kept that project file from a month back and if I load that project, I don't seem to get the problem I'm describing above!

How can this be?  All new projects I load up now contain this 'audio vanishing' bug on Hollywood Strings, (barring, for some baffling reason, Dbl Basses) and yet that initial test project from a month ago seems unaffected which is why I guess I'm scratching around here bothering you folks for clues.  I can even load up this working test project into one Sonar window and build a like-for-like version in another Sonar window and the old test project will keep HS audio hooked up and the new project will not.

Needless to say, I've done side-by-side comparisons of Sonar project settings between the working project and all those that I create from now on and can't seem to find any discrepancies anywhere.  I'm totally at an impasse.  I'm having a hard time thinking in what area I should even be looking at now.  If anyone here can take a look at this for me and offer any possible clues or suggestions I'd really appreciate the help.

Thanks for reading anyway.

Is the MIDI data still visible? If so try going to Preferences / MIDI / and increase your playback buffer. Hope that helps.

I have the same problem with Hollywood Strings.... I think it started with the latest update of their play-engine. It's really frustrating and EW/QL are terrible when it comes to support.. :/

It's strange ni other EW/QL library acts this way though. Only HS :/

Leadfoot
Is the MIDI data still visible? If so try going to Preferences / MIDI / and increase your playback buffer. Hope that helps.

That sounds like good advice and I appreciate the suggestion but I'm going to hold off making a change like that as everything else seems to be working OK.  It's been a few days since I opened the thread on this and there's possibly some refinements I need to make to my initial post.

Loptec
I have the same problem with Hollywood Strings.... I think it started with the latest update of their play-engine. It's really frustrating and EW/QL are terrible when it comes to support.. :/

It's strange ni other EW/QL library acts this way though. Only HS :/

Thanks Loptec, always nice to know you're not alone with a problem like this.  Had a bit of a hectic week and had no chance to review all this.  As I mentioned to Leadfoot above, I think it would be useful to revisit my original thread - maybe start new although it's looking less and less likely it's a Sonar issue - as there have been a few developments, one from soundsonline, stuff I need to test out.  Hopefully this weekend I'll at least be able to make a more succinct description of the problem as far as I see it, my original thread contains errors that cloud the issue.  As the thread will likely move away from here I'll cerainly post back with a link to the soundsonline forum when I can get it into shape so it makes more sense to the mods there.

I'm still on Play 3, because when I upgraded to Play 4 things got really crazy...but I've had the same problem as you with Hollywood Strings in the past with Play 3, always solved by adjusting the playback buffer, even if just by a small amount. Not sure why you'd want to "hold off making a change like that", because if it doesn't work, you can just set it back without any effect on your project. 

The adjustment to that buffer is not destructive in any sense whatsoever.  It just give it more room/time to prepare for what it has to do.
 
I agree with Mel, and anyone else, with you going ahead and making the adjustments to the midi buffers.  One set of them, cannot recall which at the moment, were dropped from earlier release values of 500, down to current levels of 250 (might be 256).  In any case, LOTS of folks bumped those back up to 500, and some have gone up to 750, and some up to 1000.
 
Sooooo, point being is that you can certainly adjust those buffers, and it just might be THAT simple to fix your current issue.  If not, you can simply move the buffer size back down.  You won't break anything with adjusting these buffers.  :)
 
Bob Bone