Hello,
Problem is most likely not 1.6ZF, since i have XFree86-pre_4.4.0
running on a Alpha Station 500 (also on a 164LX) both run 1.6ZF compiled
src and xsrc with new gcc see http://www.caseydoodle.com/index1.html 
Your kernel config or /etc/X11/XF86Config or the Matrox card may be your
problem. As i indicated if you need my help, i offer it-send me your
kernel file/var/log/XFree86.0.log as well as your /etc/X11/XF86Config
files. I can send a test 1.6ZF kernel as well  as  my working files. Do
you have any other vga cards??
-Mel

>I just today compiled 4.2.1, from caseydoodle.com, and it is
>also a no go.

>I wonder what exactly is the problem, because 1.6T + 4.2.1 and
>the same video card did work just a few weeks ago.

>Either T -> ZF is to blame, or - this is a stretch - the fact
>that the PCI config has changed slightly: different NIC and
>an new IDE card. Or... new GCC produces bad code.
-- 
mel kravitz <melk@switchpwr.com>
switching power inc