EDIT: See post #13 for the solution. I was playing around with a project that had 16 instances of Dim Pro v1.5 x64 VSTi loaded, all playing the same piano Patch, and I was seeing how many notes I could play simultaneously a la the load test described by the OP in the "Problem with the SONAR CPU meter please....?" thread - holding the sustain pedal, and playing all notes up the keyboard until the CPU overloads.
I got about half way up the keyboard when the crackles started getting pretty intense, and my CPU meters were pretty much pegged. A moment later, the audio engine dropped out. After toggling it back on, I got all my Dim Pro instances back, but when I tried to repeat the test, I found that none of them were responding to the sustain pedal. All notes would stop at Note Off, as if the sustain pedal was not sending anything.
To make a long story short, I verified that my sustain pedal is still working with hardware synths, and other soft synths. I restarted the project - No joy. I restarted SONAR. Still no joy with Dim Pro, even with a new instance in a new project, and trying different piano and E.P. patches. I tried the x64 DXi, and the Bitbridged x86 VSTi - same problem. I even cold-booted my DAW somewhere in there, but still no response to sustain in Dim Pro.
Then I recorded some sustained MIDI notes, and found that
on playback, Dim Pro would respond to them. When playing live with MIDI echoed to Dim Pro, I can see the sustain events being echoed in the MIDI track meter, and, as I said, any other synth will respond to them, but not Dim Pro.
What the heck have I done to this thing? I think this is the strangest problem I've ever encountered in SONAR.
Gonna have to pack it in for the night, and check for suggestions in the morning.