aac vs. 2610SA and Safe mode

[Vladimir Jakubal]

Hi, to whom it may concern:

[ HP ProLiant ML150, FreeBSD 6.0 (2005-11-03) ]

my server box has HP 6-port SATA RAID controller (aka Adaptec 2610SA),
common booting (as well as "ACPI disabled" mode) hang on:
aac0: COMMAND 0xx2804000 TIMEOUT AFTER xx SECONDS 
messages
Anyway, selecting "Safe mode" lets me in.
What is the difference between "Safe mode" and "default" for aac module?
Is this known bug (with probably known solution), or a new thing?

Happens any time I boot either from install CD or system on RAID-controlled HDDs.

Thanks for any reply, Hugo