In answer to your first question (asking if it's just one VST), the answer is no. I've had it hang on FM8 in one project. In another, I had it hang on Battery 3. In another, I've had it hang on MOTU.

In all three of these projects, there wasn't one common VST. For example, in the FM8 project, I only have FM8 present and no other external VSTs. In the MOTU project, I only had MOTU present with no other VSTs.

So, it's not related to one specific VST.