PANIC on 6.0-BETA-1

[dvv at online.bg]

Hello all!
Yesterday I tried moving from RELENG_5 to RELENG_6 with a custom kernel. 
Used cvsup for getting files.
Panic details follow at the end.
Here is what I did:
1. make clean in /usr/src
2. removed stale obj files.
3. commented out the NO_INFO and other knobs in /etc/make.conf  I had as 
I got error messages.
4. ran  make buildworld
5. ran make buildkernel KERNCONF=MYKERNEL. Got dependency error about 
IPDIVERT. It said IPFIREWALL was required so I commented it out.
6. removed /usr/obj/usr/srs/sys/MYKERNEL directory
7. ran make buildkernel KERNCONF=MYKERNEL
8. ran make installkernel KERNCONF=MYKERNEL

The system boots ok displaying copyright stuff, CPU features,ACPI 
stuff+links and goes booboo to here:

nvidia:0 <GEFORCE FX 5200> mem 0xde000000 - 
0xdeffffff,0xd0000000-0xd7ffffff irq 16 at device 0.0 pci "

Warning: Device driver "

Fatal trap 12: page fault while in kernel mode
fault virtual address        = 0x480008
fault cod                        = supervisor read, page not present
instruction pointer          = 0x20:0xc07ff748
stack pointer                 = 0x28:0xc14207cc
frame pointer                 = 0x28:0xc14207cc
code segment                = base 0x0, limit 0xffff, type 0x16
                                     = DPL0, pres 1, def 32 1 gran 1
processor eflags            =interrupt enabled, resume, IOPL=0
current process             =0(swapper)
trap number                  =12
panic:                           page fault
uptime 1s

The problem is I can't boot in 5.4-STABLE either
At boot up I escape to loader prompt hit boot kernel.old
Boot up and spits out
Can't work out which disk we are booting from
Guessed BIOS disk 0xffffffff not found by probes, defaulting to disk0
panic face: guard1 fail @ 0x67b44 from 
/usr/src/sys/i386/loader/../../common/modul.c:957
-> Press any key to reboot <-

A little info about my system:
512MB RAM
AMD Seprom 2500+ CPU
2 disk system - ad0 and ad1 - FreeBSD is on ad1
Have nvidia_load="YES" in loader.conf and snd_driver_all="YES"
MYKERNEL is a generic kernel I have used for 5.x series with a little 
tweaks such as COMPAT_4x, device io and mem
Sorry I can't post it but currently I do not have access to it.
Can you advise of workarounds and get back my system running?
I'm thinking of 6.0-beta1 disk2 as a start, compiling a 6.0 generic kernel.
If that fails I'm considering the 6.0-beta1 disk1 as a second resort - 
hitting upgrade button.
If that fails too - 5.4-based or some other live cd

Thanks in advance!
Have a nice day,
Dimitar Vassilev