I'm trying to get dosemu to work to it's full potential.  So far, I'm having a
few problems.  When I enable graphics, the system boots, but with a "graphics
subsystem failure" warning and it draws a picture of the card with a blinking
chip.

This is the exact same thing that happens when you put a different card that
uses com4 IRQ 3 - the conflict causes the "graphics subsystem failure."  
Because of this previous experience I'm inclined to think there's something
wrong (in my setup) with the mouse or ports or some other implementation.

With text only, I don't get the failure, but the mouse still isn't
available.  Also, the debug output mentions that there are errors in the mouse
driver module regardless of the graphics setting.  

OK - here's what I've done:
Read as much of the documentation as I'm aware of.  No errors were reported
with dosemu or kernel build, and I'm sure all version requirements are met.
I've exhausted mouse and serial port settings.  I've tried the internal
mouse driver.  I've experimented with turning "allow_video_port_access_on" and
of course, the "graphics" setting.  I tried putting 0x02e8 (com4?) in the
"ports" area.  I've tried (I'm pretty sure) every combination of the above.

"Aye captain, I've given 'er all I can!" <in my best Scotty immitation>.
Now - I'll be eternally indebted to the dosemu guru or somebody who has
experience with the ATI graphics ultra (mach 8) that can shed some light on
this snag.

Thanks in advance!
   Doug