HP DL140 G3 and FreeBSD amd64 unexpectings hangs

[Oleg Gawriloff]

We have about 20 HP DL140 G3, about 90% of them have FreeBSD amd64
installed (all 7.2-RELEASE). Sometimes (minimum once per week) all of
amd64 boxes hangs: does not react on keyboard/mouse, does not ping. On
console - black screen. On i386 or Linux we don't have any problems. If
I move HDDs with BSD to HP DL160 - all works perfectly. The problem was
detected on all version of 6.x and 7.x release-branch. Anyone is
experiencing some problems? Any solution available?