Any error messages? I've had two recent issues with my new 2010 RRS SC where after driving a few miles from cold, every single dash warning light comes on followed by multiple scrolling error messages. In both cases, "Transmission Failure" was one of the messages. The first time it happened, I lost about 90% of engine power and my power steering. I limped back home and had the vehicle towed to LR on a flatbed. Although the stored fault codes were visible, the vehicle was "perfect" during their testing and was eventually returned to me with the codes cleared and no other action taken.
Today, the same (well, similar) thing happened again - dash lights and warning messages - but the only symptom was that the transmission wouldn't shift out of low gear. Shutting off and restarting changed nothing, but a 5 minute shutdown and restart restored "normal" operation with just the check engine light on in the dash. I was able to drive it to the dealership, and it's currently awaiting diagnostics and the recent Service Bulletin/recall, which I hope addresses the issues.
This doesn't sound exactly like what you're experiencing, but may be related to what the update addresses. Hopefully, you get your vehicle back soon (same for me). In the meantime,I'm driving a Jag XK, which is a nice car but it's no RRS SC. Unfortunately, my confidence in this brand is slowly eroding, but I know that new models have teething problems which will eventually be worked out. I just have to be patient and let the process run its course. This is the price we sometimes must pay for being "early adopters".