Try frist 2.1 and after that 3.0b1.Tried twice to upgrade from a 2.0 system. No Joy. Had to uninstall before installing 3.0.
You should use bigger power adapter ... 12v @ 1.0-1.2AMy problem was in power adapter!
I try to other power adapter (12V/300mA) and all it was OK
Just tip: Try to disable connection tracking ...The RB already needs my attention do to some wierd bandwidth problem. It fails after about 6 hours and requires reboot, but the watchdog doesn't reboot it. It's not lockedup, just becomes extremely slow passing packets to ethernet1(WAN).