I have the similar problem on my home computer. I have SB600 SATA controller and see "softreset failed" messages during startup.
My Ubuntu 9.04 x64 works fine but I have soft-RAID 5 (mdadm) and this raid start recalculation of all checksumms on each reboot. On this moment I just keep my computer online whole day.
I will provide technical details later.
I have the similar problem on my home computer. I have SB600 SATA controller and see "softreset failed" messages during startup.
My Ubuntu 9.04 x64 works fine but I have soft-RAID 5 (mdadm) and this raid start recalculation of all checksumms on each reboot. On this moment I just keep my computer online whole day.
I will provide technical details later.
I hope this but will be fixed soon.