Comment 61 for bug 762203

After upgrading to kernel 2.6.38-11-generic, shutdown now completes properly on my MSI 135 laptop running 11.04 off a 4G usb stick.
An 8G stick with 10.10 will shutdown with a dirty filesystem 25% of the time. Never had problems with 10.10 on 4G sticks, so maybe the speed of the root media is an issue. The 8G usb light blinks right up to the fraction of a second that power is cut, so maybe a buffer is not getting fully written out.