I saw several posts here regarding regarding shutdown problem but this is very specific. I'm using grub4dos 0.4.5b and BT5R1 on Samsung R580 laptop. I'm able to login to BT5 but when issue shutdown command. It hung on:

casper is resyncing snapshots and caching reboot files..

I had to unclean shutdown and it corrupted casper_rw file. I tried it on a different laptop but got the same problem.
Anyway, I decided to fix casper_rw by booting into fedora 15 and issued the following command

fsck.ext2 -f casper_rw (my is ext2)

after fixing the file. I got this error when reloaded it

initrd /casper/initrd.gz

Error 15: File not found

So the casper file technique is very iffy and unreliable.