After going through all the updates, X1-X1a-X1b-X2-X2a, I am still getting crashes that lock up the system, leaving no choice but to go to cold reboot. . I have a new computer, bought specifically to run Sonar and the only add on I use is Guitar Rig 5. All the rest is exterior MIDI, and most of that is Roland (Sonar's owner). Is this a common state of affairs? Is there a known cure?

You may have a bad memory chip or other hardware issues. Is there an error message when it crashes? 

Try this: 
Run the Windows 7 memory test.
Run a FULL virus scan.
Make sure you have the latest drivers for your audio device and use ASIO mode. 

Could you list your system hardware? Are you using an ASUS motherboard by any chance?

Please define "lock up"....

Could be a bad driver.