Fedora xen - Jan 2007 - HVM guest does not start anymore (dma_timer_expiry)

Hi,

I''m using Xen on a FC6 (x86_64) system (Dell E521, AMD X2 4200 with
Pacifica-Support) with a number of different guest systems (paravirtualized as
well as fully virtualized ones). One of these is a FC6 (i386), running in HVM
mode (because AFAIK x86_64 Xen does not support i386 paravirtualized guests).
Everything worked fine so far. Today, I did a yum update in the guest machine,
loading the updates of the last 2-3 weeks. This was okay to. Unfortunately, the
guest won''t start anymore.

I''m getting these boot messages (manually typed in here, typing errors
may be
present):
...
no fstab.sys, mounting internal defaults
Switching to new root and running init.
unmounting old /dev
unmounting old /proc
unmounting old /sys
... wait for some time ...
hda: DMA interrupt recovery
hda: lost interrupt
hda: dma_timer_expiry: dma status == 0x24
(again and again)

My host system is fully patched as as of 01/06/2007 and so is the guest system.
As a special exception, I am running kernel version
2.6.18-1.2857.4.2.fc6.0.2.sctxen on the host system in order to get my Broadcom
network chipset working.

I can boot the guest just fine using qemu from Fedora Extras.

Other HVM guests (such as FC5 i386) are booting just fine.

Any ideas?
fs