problems with FreeBSD-5.1 any progam goes core

[RJ45]

pid 19543 (cc1), uid 0: exited on signal 4 (core dumped)
pid 20066 (cc1), uid 0: exited on signal 4 (core dumped)
pid 21680 (cc1), uid 0: exited on signal 4 (core dumped)

hello, suddently on my system happens that any running program
crashes with signal 4 or signal 10 and dumps a core.
This happens also when I Am compiling programs.
I Was compiling sendmail and I had to do it 4 times to have success
because the compilation was always failing all the time with cc1 system
error.
I suspect there is some bad hardware here.
the machine is a Dell power edge 2650 with 2 Xeon CPUs.
I tested all the memory modules and the memory modules are ok.
I used the Dell diagnostic program.
Could it be a CPU problem ?
I don't really know what to do anymore, progams are crashing on the
machine and it is a mail server.
anyone has some hint to help me track the problem ?
thanks

Rick