FreeBSD boot loader halts

[Simon]

Hello,

Can someone suggest a way to debug FreeBSD's boot loader?

My FBSD 6.2 freezes at random after printing Default: F1 I haven't
noticed this issue in the past with older versions of FreeBSD.
Since this is a random issue, it's very hard to pin point the culprit
by process of elimination (disabling APCI, etc...) After several
ctrl+alt+delete reboots, the system does boot. Once booted I can
run makeworld for a week without any issues. Perhaps a disk issue?
I'm booting off a MegaRAID controller. Though I cannot crash
the system using intensive IO after it boots. After it boots, it seems
to be rock solid, so I'm lost here.

Can boot loader be put into verbose mode and have it output
debugging info?

Thank you!
Simon