dual monitor problems

I've recently installed a second grfx card and am trying to run dual-head monitors. It seems to work pretty well most of the time, but now it freezes the system if I try to do any of the following: + run SaX2 + configure Date/Time through Yast + insert a USB jump drive And I mean freezes completely: I have to unplug my machine to unlock it. I'm running Suse Personal 9.1 on an Athlon processor. My cards are a Diamond Radeon 7000 and an older Matrox card. Any suggestions? T. Daniel