Boot loader messed up - How do I fix?

[Rudy Rucker]

I did a cvsup & made a new kernel & world  on August 9th but now I can't 
boot.

This was on my second drive.  When I boot, I get this menu:

  F1: ??
  F2: FreeBSD   (old, May 31st FreeBSD 6.0 CURRENT)
  F5: Drive 2   (newer, Aug 9th FreeBSD - CURRENT)

F2 works fine.  F5 _used_ to go to my other drive and boot FreeBSD just 
fine.  I have updated along the CURRENT branch many times, so I sort of 
know what I am doing ;)

If I edit the fstab file on Drive 1 to mount only points on Drive 2, the 
boot loader will load the kernel from the first drive, but then 
everything else works fine on Drive 2.

Here are my questions:
  Why is the boot code on Drive 1 unable to load the kernel on Drive 2?
  How do I fix my computer to boot the kernel on Disk 2?

(Would changing my supfile to grab RELENG_6 resolve this problem?
  I am trying that right now...)

Rudy