I flashed a clean 4GB SD card with raspbmc, and ran it on my Pi. It progresses through the installer but gets stuck in a reboot loop:
'R' screen -> "Relax, XBMC will resume shortly..." -> Blue "Updating XBMC" -> 'R' screen -> etc...
Pulling the power doesn't help, it reverts back to this cycle, except instead of the blue "Updating XBMC" screen there's a few lines of text, ending with "Mounting local filesystems: failed". Pressing esc to get to the terminal gets me to a black screen, I can't type at all. Nothing is connected to the Pi apart from a USB keyboard. I've reflashed the card twice, and the same thing happens. What's going on?