try setting noapci and nolapic on bootup. Edit your /boot/grub/menu.lst and on the line that says kernel (for your current kernel) add "noapic nolapic" so it should look somethingl ike this:
kernel /vmlinuz-2.6.10-master-r2 root=/dev/hda4 ro noapic nolapic
This disables apic and lapic on boot up, without these flags for example the A7N8X-X motherboards wont work properly (gives you DMA timer expiry's like crazy). Try it.