I always call the sudo halt or sudo shutdown or sudo reboot. This time I did not touch nor use command line: everything happened from raspi-config: by setting the enlarge partition to entire SD option. After the reboot I see some EXT4-fs errors (ext4_mb_generate_buddy, JBD2...): ext4_mb_generate_bud...

Just reflash the SD card. This happened to me some times and this is how I fixed the problem.

No, I did not modify the clock speed. I read somewhere that the sd card corruption may be a bug introduced with a new raspbian release. After some days of holidays I reconnect my PI. I found out that my SD is not fully allocated so I used the raspi-config to allocate the whole space. Then I clicked ...

This may be the fourth time I flash the 2012-12-16 rom on my SD. After one or two days my raspberry does not boot again. Sometimes it was a sintax error in a script (after an apt-get update of the ditro), sometimes a io error. This time my boot process hangs for some minutes after the usb ethernet i...