There must be some strange things going on in the Cubase mind. My project maxes out the Cubase cpu meter, and often will not play. However, I disabled plugin lanes on a few tracks, including the stereo out, to get my project to play. I made some changes to the project mix, etc.
I then started re-enabling the plugin lanes one by one, and my project continues to play, even though the cpu meter was at or near the peak. I was able to make several other adjustments and my project would still play. This was going ok for a little while. I had been enabling and disabling tracks, adding and adjusting plugins, and still I could play with all plugins in use.
Then as a final tweak with the project not playing, I adjusted a couple of fader positions in the mix console window on other tracks, and BAM! My project will no longer play.
What might Cubase have going on that would cause this? To me it seems like more leaking of resources, or misappropriating cpu power.