freebsd dies freequently

[Jian Guang Xu]

I'm experiencing frequent freeze in my FreeBSD with out any error
message. I don't know what exactly the reason is and I can only put my
current dead system information here:
The system is 5.3RC1, KDE, Firefox without flash plugin yet, Konsole
is dong "make install clean" at /usr/ports/www/mozilla.

This is a dual boot machine with W2K in the first 25G and FreeBSD in
the rest. The CPU is AMD Athlon 1600+ and 1024 Giga Ram, 3 sticks with
512mb+256mb+256mb. GeForce 2 with 32 MB, AC97 on board Audio device.

Most of the dying time for BSD is when I doing online surfing using
firefox without Flash plugin. Another thing need to be noticed is that
my /var is an independent partition approaching 83% at least.

It would be great that if somebody could at least point me somewhere
to go. Thank you in advance.

Kind Regards,
JX