FreeBSD 5.4 + DELL CERC SATA 1.5/6ch PCI card (Adaptec)

    I'm trying to install anything on my Dell SC 1420:  512 MB, SATA 
40GB, with SATA 0 and PATA-2 both enabled and RAID off.  Attempting 
FreeBSD 5.4 and 5.3 installation, both stop at "Waiting 15 secs for SCSI 
drives to settle".  Just prior to this message is "ad4: 38146MB ,WDC 
WD400BD-75JM......... at ata2-master SATA150", and the only  If I escape 
into loader prompt, type "load  aac", followed by lsmod I will see at 
the end "modules: aac.1".  I then type boot and very early see barely a 
quick glimpse of a message about aac not registering, the number 17, and 
then the boot process stops at the same "Waiting 15secs for SCSI drives 
to settle".  What else do I need to do in order to figure out what is 
going on with this computer?  By the way, the man page for the aac 
driver states
"This driver is not compatible with Dell controllers that have version 
1.x firmware. The firmware version is the same as the kernel version 
printed in the BIOS POST and driver attach messages." During boot 
process a message states "BIOS Revision A02".  Last bit of information: 
when trying to install in verbose mode there are messages about the 
ATA-2 master controller and information about ad4 drive, then "ar 
FreeBSD check1 failed".

 At the same time, I have tried to install Mandrake 10 and the process 
stops when it the attempts to install disk drivers.  Any suggestions on 
how to solve this problem will be greatly appreciated.  Thanks.  Luis