OK, DragonBlood.  M misunderstanding based on some other comments.
 
Sounds like this is a tricky one.  Good luck.

Happens to me simply by loading it in a running project. Not all the time, but it does happen.

I had the same problem with VX-64.  I am using Sonar X3 and although I am about to upgrade my computer, I have been using it successfully on an older laptop.  It was fast enough but I only had 4GB RAM.  I suspect that this is the problem with some plugins that may be memory hungry.  It doesn't matter how you instantiate VX-64, whether by dragging or selecting from the menu, if there is not enough RAM, it just freaks as the OP said.  What I get is a click when I instantiate the plugin and no more audio.  I have one project that uses VX-64 but I wanted another instance of it in another track and that was the result.  I tried getting more RAM for this machine but there were compatibility problems, even after a BIOS update.  So I thought I would just upgrade the whole lot.  New computer this week with 16GB RAM and hopefully no more issues with VX-64 or some other heavy plugins.

Yeah. Really weird.
 
Can't reproduce in a logical way.
 
Maybe it's just me, but disabling the VX-64 internal EQ retrieves the sound back.
 
What I do too is close/open the project until the issue go away.

Yep, I have had it do that too.  I could instantiate the plugin but as soon as I enabled EQ, I got the click and no audio. 

Hrm... Haven't experienced this but with all the info about eq coule this be tied in with the issues of pentagon and the valleys simulators??

GuitarLegend
Yep, I have had it do that too.  I could instantiate the plugin but as soon as I enabled EQ, I got the click and no audio. 

Wow. Two cases can't be a coincidence.
 
Problem is, there's no recipe to reproduce the issue.
 
It comes and go as a ghost .
 
Disabling the internal EQ seems to be the only workaround.

I have what seems to be a workaround: Type E to turn off all the effects, then type E to turn them on again. Fixes it most of the time. I've inquired about this bug and been told it's on the "to be fixed" list, it's not being ignored. Oddly, I haven't had it happen since upgrading to Platinum but I didn't see the fix on Noel's list so I assume it's coincidence or I simply haven't been using the VX-64 enough.

Tried to load it yesterday on a 48khz project and the VX caused a feedback on the strip (meters cliping and all). Loaded it on another project (44 kHz) and it was fine... Could sampling rates be a cause?
 

I've had it happen at 44.1 kHz. Still haven't had this issue since running Platinum, but don't know if that's because something happened that fixed it, or the "intermittent ghost" is waiting in the wings and getting ready to strike.