I had issues with my RPi running Raspbian freezing/crashing for almost two weeks, but have now been up and running for 3 days since following the advice in this thread- http://www.raspberrypi.org/forums/viewtopic.php?f=28&t=70437

I appreciate the help of everyone in this thread, hopefully this info can help others.

One question for you pros out there; now that it's running stable, every so hours one of my miners will stop working and instead of hashing cgminer shows it as "OFF". Simply turning the powered USB hub and then back on gets everything working again, but it's a little frustrating. It's happened a few times and is a different unit every time, so I can't see it being a problem with the hub or a cable. Any suggestions?