Weird reboots from bootmgr or loader

Hello everyone !

I got a really anoying Problem today. 3 different boxes started to reboot
when i hit enter at the bootmgr, or when i don't hit enter and wait for it
to boot FreeBSD it reboots when the loader should apear. I can see that it
prints out some numbers but its to fast to recognise anything. I did not
mess with the disk configuration on any of the boxes. I only rebuild world
and kernel as usual every few days. They all had sources from 3rd or 4th
of august. I don't have my serial cable handy i'll try to get it back this
evening and see if i can provide any further information. One thing that
might be special is that they all have -march={p2,pentium3,pentium4} in
make.conf.
I don't have *any* clue what might happen here.

Regards,
flo