Problem with ECS k7s5a and ATI Radeon

[Laurent Mouillart]

When exiting an X window session normally all looks good.
When I switching to a virtual console <ctl><alt><Fn> all looks good too.
But when killing it with <ctl><alt><bkspc> (every time berfore the
window are completly loaded, somtimes when window manager are completly
loaded)system reboot.

I used an ECS k7s5a with radeon 64vivo under recently updated debian sid
+ Linux-2.4.13-ac7.
When i enable in BIOS:
ACPI
PowerManagement
PNP OS

System print "hda irq lose" and hang.