What you're describing sounds nearly EXACTLY like what I'm getting with my new Virus TI2 Polar. I've been dialoging with support and they are now coming to the conclusion that there is an issue with the unit itself.
BTW, I have a completely different setup to yours (Mac OS X 10.5, Logic 8/9). I'd definitely recommend contacting support.
Thanks for the tip. I think I will do so! It is really really frustrating. The performance is so random, I couldn't even bet if it works every time I turn it on. I think I'll get to support right away.