new Ultra 5 "reproducible" XF86_Mach64 lockups

[Hein Roehrig <hein@acm.org>]

Hello,

I have a problem with XF86_Mach64 crashing and/or locking up the
system when the "jigsaw" screen saver has run for a few minutes.

The system is running up-to-date Debian potato with xserver-mach64
3.3.6-7 and xscreensaver 3.22-7. Different kernels (stock 2.2.15-2 and
self-compiled 2.2.16) don't make a difference, nor does the setting of
the monitor power management (DPMS on/off). Running a Gnome session,
no error message appears in /var/log/gdm, and running

xinit /usr/bin/X11/jigsaw -root

once resulted in 

-----------
X error in jigsaw:

X Error of failed request: Bad Alloc (insufficient resources for
                                      operation)

Major opcode of failed request: 53(X_CreatePixmap)

Serial number of failed request: 423979

Current serial number in output stream 423984

waiting for X server to shut down
-----------

but most of the times just kills the X server, leaving the text 
console in a mostly unusable state.

Thanks in advance for any advice,
Hein