Pkg xen devel - Oct 2012 - Bug#674907: shifts the clock by 50 minutes unexplicably under a Xen dom0

I have exactly the same problem.
I have two cluster nodes HP Proliant DL 580 G5 systems with four quad
core Xeon processors.
Operating system is debian squeeze.
Uname -a:

Linux xen-p02 2.6.32-5-xen-amd64 #1 SMP Sun Sep 23 13:49:30 UTC 2012
x86_64 GNU/Linux

This is an annoying problem, the system clock in dom0 jumps forward 50
minutes and this cause my cluster node to be fenced and then rebooted.
There is a lot of people that have this problem.
Why it is set to normal severity? I think it is a very grave problem,
systems are unusable and it seems that there isn't a workaround.
Still don't know if it is a xen problem or a debian kernel problem.
Do you think think it might be found a solution?
I'm in troubles.
Thank you.

I want to add this log messages in kern.log

Sep 30 23:21:12 xen-p01 kernel: [104363.072636] Clocksource tsc
unstable (delta = -811538939738 ns)
Sep 30 23:21:13 xen-p01 kernel: [104363.189879]  [<ffffffff8105b6e0>]
? run_timer_softirq+0x196/0x268