boot failure

[Roadrunner]

I created the CD's from the ISO images rel 5.0 upon booting from the cd rom the installation will fail with the message
PANIC PMAP_MAPDEV: COULDN'T  ALLOC KERNAL VIRTUAL MEMORY. It will then reboot the system my conf is an AMD Duron 1.9 ghz 256 meg ram two 40 gb hard drives on primary controller two cd rom drives on sec controller booting from the master cd rom drive. What could be causing that error mess to come up?