Weird lockups on KM400 Mobo with 2.6 kernel

[Thrifty]

Hi !!

I am really stuck here, I have a Gigabyte motherboard with KM400A chipset and 8237 Southbridge. I have set up Gentoo on it and it boots with the 2.6.4 gentoo-dev-sources fine, however whenever there is any major disk access the system seems to "freeze"

The cursor keeps flashing but I cannot access the machine, canot type any commands and basically have to reset it!

It runs fine off the 2004.0 live cd with kernel 2.4

Is this a common thing, or am I the first to encounter this problem.

Any help is really appreciated!