Weird Crash problem

[David Kalliecharan]

Hello Everyone!
I am very new to the scene of FreeBSD. Most of my basic Knowledge comes
linux but I wan to learn about FreeBSD. I have installed FreeBSD 6.1 stable
and have the graphical system up and running but I find that after a hour or
so, or when I try to open certian applications or install a application via
the ports system, the screen acts funny (I believe it has to do with the
refresh rate somewhat) And I see odd lines that appear randomly and take up
the whole screen eventually. Then after a bit I have no mouse control and
then Xorg crashes which locks up the system and then I reboot using Ctrl +
Alt + Delete. This works but causes another problem where I must run fsck
manually and fix damage to the harddrive? The harddrive has been tested and
is fine except when Xorg crashes like how I explained. The Xorg I use is a
binary from the install CD. Should I upon install upgrade the Ports tree and
then install all the applications I need or is there another lingering
problem that I am not aware of?
Thanks
-- 
Dave