Problems booting my computer

[Darksidex]

A few days ago I tried to compile and install FreeBSD 5.3-p2 from a 
FreeBSD 5.3-p1
Everething worked until I wanted to make installword. I switched to 
single mode, and during the installation my computer stoped and shaw me 
a error (I don't remember it). I had to reboot, and booting process 
stopped with some hexadecimal characters and with the string "BTX Halted".

I downloaded the second disc of FBSD 5.3 release, and I could fix the 
disk, and I could copy /boot/kernel directory from cd to my disk.
But when I try to boot up my computer it stops with this message:

Mounting root from ufs: /dev/ad1s1a
pid 49 (sh), uid 0: exited on signal 4
Dec 23... init: /bin/sh on /etc/rc terminated
abnormally, going to single user mode
Enter root password, or ^D to go multi-user
Password:
Enter full path name for shell or RETURN for /bin/sh:

And it doesn't matter what type of shell I want to use, it stops with 
the same message (pid # (...), uid 0: exited ...)

What can I do?