I recently purchased Melda Productions - MReverb. As soon as I insert it in a project (X1)and playback, it spikes the audio (with a concurrent high shrill) and stops the playback with an error message about audo engine stopping. Any ideas. I wonder just in general why a plug in can cause that - I think its happened a long time ago. I have written to them, but thought I would try here in the meantime.

I'm guessing any reverb can potentially do that, if it's not specifically coded not to. Algorithmic reverbs are all about feedback loops. Ever try Valhalla Shimmer? It can make a reverb tail that never ends. It's a short hop from that to runaway feedback. Maybe you had a very long reverb time set up? I'm thinking it's a bug that Vojtech would want to hear about, assuming you can reproduce it.