This has been a recurring issue from my use of SONAR.  I am back to a new project and have the same issue again.  Playback of the song in SONAR is flwless. i.e., without artefact.  I Export audio as a wave or 128kb MP3 with fast bounce, 64 bit engine, power3 dither all on, with no other softwarethat I am aware of running..  Then on play back of the exported song, I hear at least one millsecond artefact somewhere in the song, an artefact lick a millsecond crack/crakle. I need to go back and export audio again and hope that another artefac t is not created.  Out of 3-4 tries, I get one that is without artefact and I can include it in the final master.  How do I identify if there is another process that is causing the glitch/artefact?

 Perhaps disable dither on output?

you hear the artifact, but do you see it? I am wondering if the playback is hosed. You mentioned nothing visually.
 
Are you bouncing all tracks to a single track first? Are you freezing your synths first?
 
I always bounce to track first before exporting. That way I know what the mix will be like before exporting.

Is the crackle happening at the same spot after any given export?  Not clear from your post if the file itself has the error, or if there is just a playback issue.  If the crackle is at the same spot after several plays, or if you can see it in the waveform, you'll know.

If the glitch is visible in the exported waveform, try increasing your ASIO buffer to 256 samples or more if it's below that. SONAR uses your ASIO buffer size by default for offline (Fast Bounce) processing, and some Plugins don't like doing Fast Bounce with a very small buffer. If that solves it, you can go into AUD.INI, and set BounceBufSizeMsec=5 or higher; I have mine at 20.

Export to a 24bit undithered file, using the 64 bit engine
 
Reimport it into your project
 
Now you can easily compare the 2.
 
If it's ok, try Exporting to 16bit WITH dither and repeat the import process (for CD burning)
 
Only once you've got a reliable wav should you convert to mp3, in my opinion.

Your probably clipping the output. You may not hear it in playback since your in 32bit floating point, but you will hear it when you export. Make sure you are not clipping.

The easiest thing to try is a slow bounce. But if the problem is being caused by memory exhaustion, try an export with the 64-bit option turned off. This is assuming the glitch is caused by a dropout rather than clipping.