Kernel BUG at kernel/timer.c:681 and broken ext4

I just ran into a mysterious issue with a Virtualbox virtual machine running linux kernel 2.6.37-rc1 (although this might not be kernel specific). After a power outage, reboot always ended with a kernel panic with the following message (among a rather long screen dump):

Clocksource tsc unstable (delta = 784015673 ns)

---[ end trace a732f57055898f20 ]---

Switching to clocksource acpi_pm

Kernel panic - not syncing: Attempted to kill init!

[...]

kernel BUG at kernel/timer.c:681!

invalid opcode: 0000 [#1]

last sysfs file:

CPU0

Modules linked in:

[...]

First, I found many forum posts stating that tsc clocksource has to be replaced with acpi_pm (or something else) already in GRUB, but this didn't help. Then I figured that in recovery mode, having fsck to repair the root filesystem, puts it back to normal. So: even though it does not seem to be related, a broken filesystem can cause the kernel panic above!