I think the X2 patch coming for Win 8 is for the touch-screen functionality. I use Win 8 with X2 all day and have no issues whatsoever with stability.
You DO have to make sure you have the correct drivers installed - and any USB device may not properly work yet with the USB 3.0 ports - as the other poster indicated, I too have a Presonus USB interface, and USB 3.0 made it completely freak out, but it works fine with the USB 2.0 ports.
Questions:
Do these blue screens etc. happen outside of attempting to use Sonar?
Do they happen if you have your interface unplugged from the computer?
Do normal tunes play through Windows Media Player?
In Device Manager, are all of your drivers indicating working properly?
What happens if you plug your interface into a USB 2.0 port?
Have you checked the ASIO sample rates to make sure they match between Sonar and the interface?
Please respond to the above questions - maybe something there will point to an issue that can be resolved,
Bob Bone