I have a stable GigaStudio 4 rig running on x64. I'm hesitant to make a change since I can't rely on VE Pro in this state and have to keep working. But I'll buy a copy of W7 Ultimate and put it on a different (swappable) startup drive for testing.
Here's how I recreate the bug:
1. Boot up computer and start VE Pro Server (32-bit)
2. Delete default instrument, add Kontakt 3.5
3. Load a few sounds then save the Mframe
4. Quit VE Pro
5. Launch VE Pro and open the Mframe
6. VE Pro reports "Missing plug-in: Kontakt 3." When I right click in the left column I no longer have a VSTi option that lists my plug-ins. I have to reboot the computer to see my plug-ins again.
I've tried the above with GVI 3 and GVI 4 with the same result.