Specific Rewire latency/glitching issue

Hey folks,

Just upgraded from Home Studio 7 to Sonar X2 - great features, but a whole plethora of bugs and issues. I'll stick to two seemingly related ones now:

I'm running X2, Windows 7, Rewire to Reason 4, audio interface a Tascam US-122L, 48 khz/24 bit (both X2 and Tascam).  Except for the recent X2 upgrade, I've always used the same setup and it's worked fine.

When I run the Wave Profiler, everything seems to work perfectly fine, for the moment. However, after hitting a few notes on my MIDI controller to activate Reason, a huge consistent latency of at least a second occurs. Furthermore, after working for a few minutes, the Rewire playback goes completely out of sync, glitches all over the place, and adopts some sort of strange delay (repeating short clips maybe once a second).

Any ideas? I should note that the strange delay that occurs seem to be almost the same tempo as the delay set in the z3ta+ I'm also running in this session, though I suspect it's a coincidence. In the routing the two aren't even remotely connected. 

Thanks a lot, I really need to get this sorted out.