weird ufs corruption on amd64

Hello,
recently I decided to install -current on one of my computers but I ran
into a problem with reading files from UFS:
- some of the files have a part of them replaced
- when I try to read them in 6-stable, they are fine; /boot/loader is
  always able to load kernel too
- only files greater than 64KB are affected
- the part that is replaced seems to be always 64KB big but doesn't
  begin on 64KB boundary
- the data is usually replaced by \000s but sometimes it seems like
  a part of another file
- the corrupted file(s) do not change unless I reboot/remount the fs
- I have tried writing but didn't test it thoroughly; it seems to work
  without any problems (the files are readable from -stable just fine)

The system is an uniprocessor Tyan S3970 (Broadcomm chipset) with Opteron
2210, 2GB RAM and 3 250GB disks. It works under -stable from last week just
fine (dmesg is attached as 6_2.boot). I tried installing -current
according to instructions in src/UPDATING (onto a separate partition):
env -i make buildworld buildkernel # KERNCONF=GENERIC
env -i make installworld distribution installkernel DESTDIR=...
# edit ${DESTDIR}/etc/fstab etc.
and it worked but kldxref complained about unknown metdata record (see
attached file installkernel.err) - I'm not using any modules though.
I'm attaching the dmesg from -current too (curr_a.boot).
I tried waiting a couple of days, cvsupping new -current and trying it
out but it behaved the same.

Any help would be greatly appreciated, if you need some information I
did not provide, let me know how to get it please and I shall post it to
the list.

Matej Kubik

PS: Sorry for my bad English, I'm not used to speaking it. ;-) Hope you
can understand.