"PCI: Cannot Allocate resource ... " when adding graphic card

["Reuben D. Budiardja" <techlist pathfinder phys utk edu>]

Hello,
I have a machine with NVIDIA GE Force FX 5500 on AGP slot that works just 
fine. I have a PCI Matrox Millenium II card lying around, and so I tried to 
put it in so that I can have a dual-head display. After I put in the Matrox 
card to the available PCI slot, when booting I got the message:

"PCI: Cannot allocate resource region 1 of device ... "

When I try to startx, the machine would hang and won't even respond to 
CTRL-ALT-DEL to reboot. system-config-display won't work either. I believe 
this is because of the PCI message above. 

Any suggestion as to what cause this, and how to fix it ? Is it possible to 
have a dual-head display with AGP Nvidia card and PCI Matrox card ? I've done 
something similar with an onboard trident card, and a matrox PCI card before 
and it works just fine.

Any help is appreaciated. Thank you

Reuben D. Budiardja