I tested with the Amulet on my win7x64 htpc and I have no such problems there either, but I am only locking it for a minute, and I did not try bashing the mouse and keyboard around.
No VC does not seem to work when the PC is locked. I think that all normal program execution is suspended (on purpose) when windows is locked. I probably could get around this by turning VC into a service but i have no intention of doing this.
Try the screensaver idea but also let me know if turning it off then on works.
USBUIRT works great with VC, but if you want to use it with both, I'm not sure if there will be a conflict between EG and VC both accessing it at the same time.
Yeah voice controlling lights is fun and I especially like voice commands for complex macros like "watch TV" or "listen to music", or "I'm going to bed" which does about 10 things for me. Nice thing with Vera scenes is that you can do them in timed stages so when I go to bed, it starts a Vera scene and then shuts down the TV, stereo, and computer. The Vera scene shuts the lights off slowly, over a period of about 10 minutes, giving me time to brush my teeth and get into bed without being in the dark.