FreeBSD 4.8 -lock up on new box

[anthony]

Just got a new amd xp 2700 setup with freebsd 4.8-release and when ever
attempting to upgrade the source (make buildworld), the machine locks up.
We did sucessfully install the OS from an ISP and it seemed to go fine.

Another amd I had before this one had FreeBSD 4.8-RC installed and would
lock up just like this one, with no errors or cores or anything at 'od'
times, when nothing much was running.  We upgraded to latest versions of
apache, sendmail, mysql, etc to see if that was it, and it wasnt.  We then
assumed it could be over heating and placed a fan in it... so far it seems
to be working.

The new machine has tons of fans in it, and shouldnt be over heating at
all.   Is there any suggestions you guys can give me as to what might be
causing the problems?  We did mem tests, hd tests, and all came out to be
fine.

Any help would be appreciated.
-anthony