I'm not saying what the cause is - but it may be coincidental that after this month's updates I've experienced two problems that I have not had before (and I have had the Surface RT since launch day). One - I had a BSOD. No details - and I sent the report to MS, but nothing to indicate what happened. Two - I experienced the same issue as "inteller" above. I was in Bento News, reading an article and the graphics card had a moment, causing green artifacts all over the screen. I was able to close the app, but Start screen had odd pixels out of place. I performed a shut down, and then brought the system back up. Haven't had a problem since (this was last week).
So empirically, it would seem that the latest updates did cause some stability issues, at least for me. My machine doesn't change much at all. I have the same apps I've had since the beginning. The only changes are the monthly updates. I mostly use the Surface for web browsing in IE.