FreeBSD 5.4 install problem. Newbee needs help.

[William Manley]

I am a new FreeBSD user and I have an installation that has gone bad. My 
problems started when I enabled XDM for a graphical logon into Gnome. 
When I logged in as root the system just looped back to the logon 
screen. I then assumed I had configured my .xinitrc file wrong so I 
booted the install cdrom into Fixit mode and tried to mount the root 
filesystem on the hardisk which the operating system would not let me 
do. The following are the commands I typed with the output.

mount /dev/ad0s1a /mnt
operation not permitted

disklabel -r ad0
no valid label found

ls did show something.
ls /dev/ad0*
/dev/ad0 /dev/ad0sla /dev/ad0s1c /dev/ad0s1e
/dev/ad0s1 /dev/ad0s1b /dev/ad0s1d /dev/ad0s1f

fdisk /dev/ad0
working on /dev/ad0

figures below won't work with bios for partitions not in cyl 1. 
Parameters to be used for bios calculations are:
cylinders= 77504 heads= 16 sectors/track= 63 (1008 blks/cyl)
media sector size is 512

Warning: bios sector numbering starts with sector 1

Information from DOS boot block is:
The data for partition 1 is:
sys id 165 (0xa5), (FreeBSD/NetBSD/386BSD)
start 63, size 78124032 (38146 meg) flag 80 active
beg: cly0/ head1/ sector 1
end: cyl 1023/ head 254/ sector 63

Does the warning tell me that my bios is not set up properly for FreeBSD 
to work with the hardisk setup. The handbook says to set up your bios to 
select hardisk's naturally. Before starting the install I looked at the 
bios and was not sure what to configure. Should I go to the basic page 
and set the hardisk as uninstalled? Any help in getting back into my 
system will be appreciated. If I have to reinstall I'll do it.

Bill