RC1 doesn't boot with GPT (i386) anymore

Some hours ago I upgraded from BETA7 to RC1, cvsuped today, with the same 
kernel config but now GPT doesn't work anymore.

I can't see any reason why it fails.
Here's what a verbose boot displays and below what BETA7 kernel shows:
________
RC1:
GEOM: Configure ad0s1, start 17408 length 256000000 end 256017407
GEOM: Configure ad0p2, start 256017408 length 15360000000 end 15616017407
GEOM: Configure ad0p3, start 15616017408 length 256000000 end 15872017407
GEOM: Configure ad0p4, start 15872017408 length 1024000000 end 16896017407
GEOM: Configure ad0p5, start 16896017408 length 5120000000 end 22016017407
GEOM: Configure ad0p6, start 22016017408 length 10240000000 end 32256017407
(cd0:ata1:0:0:0): error 6
(cd0:ata1:0:0:0): Unretryable Error
(cd0:ata1:0:0:0): error 6
(cd0:ata1:0:0:0): Unretryable Error
(cd0:ata1:0:0:0): error 6
(cd0:ata1:0:0:0): Unretryable Error
(cd1:ata1:0:1:0): error 6
(cd1:ata1:0:1:0): Unretryable Error
(cd1:ata1:0:1:0): error 6
(cd1:ata1:0:1:0): Unretryable Error
(cd1:ata1:0:1:0): error 6
(cd1:ata1:0:1:0): Unretryable Error
GEOM: Configure ad0s1a, start 0 length 256000000 end 255999999
GEOM: Configure ad0s1c, start 0 length 256000000 end 255999999
WARNING: Expected rawoffset 0, found 34
GEOM: Configure ad0s1a, start 0 length 256000000 end 255999999
GEOM: Configure ad0s1c, start 0 length 256000000 end 255999999
Mounting root from ufs:/dev/ad0s1a
start_init: trying /sbin/init
ums0: Microsoft Microsoft IntelliMouse® Explorer, rev 1.10/1.14, addr 2, 
iclass 3/1
ums0: 5 buttons and Z dir.
Pre-seeding PRNG: kickstart.
Loading configuration files.
Entropy harvesting: interrupts ethernet point_to_point kickstart.
swapon: /dev/ad0p2: No such file or directory
Starting file system checks:
/dev/ad0s1a: FILE SYSTEM CLEAN; SKIPPING CHECKS
/dev/ad0s1a: clean, 93566 free (1142 frags, 11553 blocks, 0.9% fragmentation)
Can't stat /dev/ad0p3: No such file or directory
Can't stat /dev/ad0p4: No such file or directory
Can't stat /dev/ad0p5: No such file or directory
Can't stat /dev/ad0p3: No such file or directory
Can't stat /dev/ad0p3: No such file or directory
/dev/ad0p3: CAN'T CHECK FILE SYSTEM.
/dev/ad0p3: UNEXPECTED INCONSISTENCY; RUN fsck MANUALLY.
Can't stat /dev/ad0p4: No such file or directory
Can't stat /dev/ad0p4: No such file or directory
/dev/ad0p4: CAN'T CHECK FILE SYSTEM.
/dev/ad0p4: UNEXPECTED INCONSISTENCY; RUN fsck MANUALLY.
Can't stat /dev/ad0p5: No such file or directory
Can't stat /dev/ad0p5: No such file or directory
/dev/ad0p5: CAN'T CHECK FILE SYSTEM.
/dev/ad0p5: UNEXPECTED INCONSISTENCY; RUN fsck MANUALLY.
Can't stat /dev/ad0p6: No such file or directory
Can't stat /dev/ad0p6: No such file or directory
Can't stat /dev/ad0p6: No such file or directory
/dev/ad0p6: CAN'T CHECK FILE SYSTEM.
/dev/ad0p6: UNEXPECTED INCONSISTENCY; RUN fsck MANUALLY.
THE FOLLOWING FILE SYSTEMS HAD AN UNEXPECTED INCONSISTENCY:
        ufs: /dev/ad0p3 (/var), ufs: /dev/ad0p4 (/tmp), ufs: /dev/ad0p5 
(/usr), ufs: /dev/ad0p6 (/builder)

_____________
BETA7:
EOM: Configure ad0s1, start 17408 length 256000000 end 256017407
GEOM: Configure ad0p2, start 256017408 length 15360000000 end 15616017407
GEOM: Configure ad0p3, start 15616017408 length 256000000 end 15872017407
GEOM: Configure ad0p4, start 15872017408 length 1024000000 end 16896017407
GEOM: Configure ad0p5, start 16896017408 length 5120000000 end 22016017407
GEOM: Configure ad0p6, start 22016017408 length 10240000000 end 32256017407
[0] f:80 typ:165 s(CHS):0/0/35 e(CHS):31/32/3 s:34 l:500000
[1] f:00 typ:0 s(CHS):0/0/0 e(CHS):0/0/0 s:0 l:0
[2] f:00 typ:0 s(CHS):0/0/0 e(CHS):0/0/0 s:0 l:0
[3] f:00 typ:0 s(CHS):0/0/0 e(CHS):0/0/0 s:0 l:0
GEOM: Configure ad0s1, start 17408 length 256000000 end 256017407
(cd1:ata1:0:1:0): error 6
(cd1:ata1:0:1:0): Unretryable Error
cd1 at ata1 bus 0 target 1 lun 0
cd1: <IDE DVD-ROM 16X 5.00> Removable CD-ROM SCSI-0 device
cd1: 33.000MB/s transfers
cd1: Attempt to query device size failed: NOT READY, Medium not present
(cd0:ata1:0:0:0): error 6
(cd0:ata1:0:0:0): Unretryable Error
(cd0:ata1:0:0:0): error 6
(cd0:ata1:0:0:0): Unretryable Error
(cd0:ata1:0:0:0): error 6
(cd0:ata1:0:0:0): Unretryable Error
(cd1:ata1:0:1:0): error 6
(cd1:ata1:0:1:0): Unretryable Error
(cd1:ata1:0:1:0): error 6
(cd1:ata1:0:1:0): Unretryable Error
(cd1:ata1:0:1:0): error 6
(cd1:ata1:0:1:0): Unretryable Error
WARNING: Expected rawoffset 0, found 34
GEOM: Configure ad0s1a, start 0 length 256000000 end 255999999
GEOM: Configure ad0s1c, start 0 length 256000000 end 255999999
GEOM: Configure ad0s1a, start 0 length 256000000 end 255999999
GEOM: Configure ad0s1c, start 0 length 256000000 end 255999999
Mounting root from ufs:/dev/ad0s1a
start_init: trying /sbin/init
ums0: Microsoft Microsoft IntelliMouse® Explorer, rev 1.10/1.14, addr 2, 
iclass 3/1
ums0: 5 buttons and Z dir.
Pre-seeding PRNG: kickstart.
Loading configuration files.
Entropy harvesting: interrupts ethernet point_to_point kickstart.
swapon: adding /dev/ad0p2 as swap device
Starting file system checks:
/dev/ad0s1a: FILE SYSTEM CLEAN; SKIPPING CHECKS
/dev/ad0s1a: clean, 93566 free (1142 frags, 11553 blocks, 0.9% fragmentation)
/dev/ad0p3: FILE SYSTEM CLEAN; SKIPPING CHECKS
/dev/ad0p3: clean, 379485 free (181 frags, 47413 blocks, 0.0% fragmentation)
/dev/ad0p4: FILE SYSTEM CLEAN; SKIPPING CHECKS
/dev/ad0p4: clean, 935860 free (28 frags, 116979 blocks, 0.0% fragmentation)
/dev/ad0p5: FILE SYSTEM CLEAN; SKIPPING CHECKS
/dev/ad0p5: clean, 4496974 free (5134 frags, 561480 blocks, 0.1% 
fragmentation)
/dev/ad0p6: FILE SYSTEM CLEAN; SKIPPING CHECKS
/dev/ad0p6: clean, 4124278 free (5246 frags, 514879 blocks, 0.1% 
fragmentation)
Setting hostname: test1.flintsbach.schmalzbauer.de.