Just recently I started getting this box in X3 32-bit. Weird it hasn't happened before. It's for a handful of plugins, none of which are actually in the list that's presented to match to. If I just click "OK" through the list (which is about twenty items) SONAR opens and everything is as it should be though.
 
Weirder still, it pops up randomly. Sometimes when I'm just editing audio, sometimes right when I hit playback, sometimes on project open. Sometimes it's just one or two plugins, sometimes a whole slew. Anybody ever get this?

Try updating to X3E and then perform a VST reset.
Get rid of the plugins you are not using.
Get rid of duplicate plugins as well.
 
BTW why are you using Sonar 32 bit on 64 bit windows? Sonar will not be able to access half of your memory.
Sonar 64 bit can handle 32 bit plugins and should be be far more stable, however the more 64 bit plugins you can give it the better.

Thanks

Will do Alex, I'll give it a shot!
I actually DO use 64-bit for everything moving forward, I specify 32-bit because I'm finishing a record started in 32-bit and most of the projects won't open at all in 64. 

Ah very sensible.... Cheers...