reboot issue …

I’ve an reboot issue:

installing CentOS 4.1, with Software RAID, all works fine
I’ve md0 to md5 with /boot, /, /swap, /home and /var
when trying to reboot I see that there is still a message:
“md1 is still in use” than the system is syncing SCSI (my HDD’s are SATA) and tells that it is rebooting but in fact it is ‘halting’ keyboard has no functionality anymore and only a hard reset on the system is possible to restart the system

What can be the cause?

Has it to do with a setting of GRUB (bootloader)
or has it to do that the md1 partition is still in use (and how to solve it) ?

Any geek an idea?