Problem with halt and grub command line dell vostro 1400

I have strange problem with dell vostro 1400. I have installed Ubuntu 7.10 and Wind Vista Bussines. Ubuntu work grat and when i shut it down it shuts down my notebook (closeing from menu or by halt command). But when i run my notebook and during boot manager i clicked c button (command-line) and write halt from that command, computer freezes not shuts down. Reboot command works ok, but halt dosen't shutdown my vostro "by hard". Is it something wrong with grub or what? Strange thing, becuse from OS all is ok, but from grub command line not