6.0-RC1: Boot panic

Hello all,

I have just updated my system from 5-STABLE to 6.0-RC1 and experienced a 
kernel panic while booting.

First it occured only few lines after the boot menu (two times at the 
same position). Then, after deleting some lines in loader.conf 
('nvidia', 'acpi_ppc' and later on everything but 'autoboot_delay="1"' 
and 'hw.ata.atapi_dma=1'), the panic came up right after the 'rtc' line 
after the kernel init (when the color turns from white to grey - I am 
too lazy to boot again, let it panic and write it down. If it is 
important, please tell me). Again, the exact position of the panic 
stayed the same. Which seems strange to me, since the panic itself 
didn't change.

The first thing printed on screen was 'Warning: Device "' (and nothing 
more) followed by the actual panic message, which looked like this:

Fatal trap 12: page fault while in kernel mode
fault virtual address   = 0xc
fault code              = supervisor read, page not present
instruction pointer     = 0x20:0xc057b4d0
stack pointer           = 0x28:0xd712fa80
frame pointer           = 0x28:0xd712fab4
code segment            = base 0x0, limit 0xfffff, type 0x1b
                         = DPL 0, pres 1, def32 1, gran 1
processor eflags        = interrupt enabled, resume, IOPL = 0
current process         = 32 (kldload)
trap number             = 12
panic: page fault

I say 'like this' because it is not the exact message. I have a kernel 
dump, but get a 'kgdb: cannot read PTD' error - if someone can tell me 
how to solve this (the mailing lists did not), I would be really pleased.

Anyway, these items I am sure of: The first line, the third line, the 
'code segment' line (not including the 'DPL ..' line) and the last two 
lines. And I am sure that the *last* panic had 'kldload' as the current 
process, but I don't know if the other panic messages had that too.

And here the info file:

Dump header from device /dev/ad0s1b
   Architecture: i386
   Architecture Version: 33554432
   Dump Length: 1072234496B (1022 MB)
   Blocksize: 512
   Dumptime: Tue Oct 11 22:55:07 2005
   Hostname: acheron.network
   Magic: FreeBSD Kernel Dump
   Version String: FreeBSD 6.0-RC1 #0: Tue Oct 11 22:47:16 UTC 2005
     tobiasmo_at_acheron.network:/usr/obj/usr/src/sys/GENERIC
   Panic String: page fault
   Dump Parity: 2875165490
   Bounds: 32
   Dump Status: good

I tested both my own kernel config and GENERIC, with the same results.

Any suggestions?

Bye,

Tobias Mohrlüder