Xbian hangs during boot saying "Switching root"

[mk01]

1) put "debug" into cmdline and let's see, how far you get.

2) put "init=/bin/bash" into cmdline to start a shell immediately after switch root. if you get shell, then it's stuck somewhere on processing /sbin/init and you should be able to see something with 1)

if you don't get shell with 2), something is messing your SD card.

how does your /etc/fstab look like? and please check for "nohdparm" option in cmdline, if it is not there, put it there.