From the dmesg logs it shows nothing about the Adaptec yet in the Status > Hardware gui your seeing it....

So from the dmesg log let's approach this at the hardware layer, try turning of any power management features of the motherboard or move to another slot to test. Any settings in the Adaptec that you can test.. turning off the BIOS or other options that might affect the issue. I know that you have removed the CD-ROM any chance you can test w/ the Demo-CD.

Coming up blank as I don't have this card with me. You can send me the whole logs and maybe something might show up.