Repeated kernel error message at read_hpet+0x14/0x20 in getnstimeofday

[Dan Kegel]

I installed Ubuntu 8.10 the day it came out on three systems.
Two of them are fine, but one of them prints a kernel error
message in /var/log/messages every twenty minutes under
load.
The affected system is an Intel Q9400 in an
ECS GF7100PVT-M 775 7100/630I RT motherboard,
using the Ubuntu-supplied restricted nvidia driver.
(The OK systems are various single and dual core
CPUs, some using the same driver, but different
motherboards.)

Here's the error message:

kernel: [ 2758.972148] Modules linked in:
 ac acpi_cpufreq af_packet agpgart ahci ata_generic battery
 binfmt_misc bitblit bluetooth bnep bridge button container
 coretemp cpufre cpufreq_ondemand cpufreq_powersave cpufreq_stats
 cpufreq_userspace crc_t10dif dock ehci_hcd evdev ext3 fan fbcon
 font forcedeth freq_table fuse hid hwmon_vid i2c_core idi_event
 ip_tables iptable_filter ipv6 jbd l2cap libata lp mbcache
 nvidia(P) ohci_hcd output parport parport_pc pata_acpi pata_amd
 pci_hotplug pci_slot pcspkr ppdev processor q_conservative
 rfcomm sbs sbshc sco scsi_mod sd_mod sg shpchp snd snd_hda_intel
 snd_mixer_oss snd_page_alloc snd_pcm snd_pcm_oss snd_rawmidi
 snd_seq snd_seq_device snd_seq_dummy snd_seq_m snd_seq_midi
 snd_seq_oss snd_timer softcursor soundcore stp thermal tileblit
 usbcore usbhid video w83627ehf wmi x_tables
kernel: [ 2758.972221]
kernel: [ 2758.972226] Pid: 5902, comm: Xorg Tainted: P (2.6.27-7-generic #1)
kernel: [ 2758.972228] EIP: 0060:[<c0118e44>] EFLAGS: 00203286 CPU: 0
kernel: [ 2758.972235] EIP is at read_hpet+0x14/0x20
kernel: [ 2758.972237] EAX: 0f9d1ebd EBX: f5431fa0 ECX: f5431f8c EDX: 12ae50cf
kernel: [ 2758.972239] ESI: bfbcd6c8 EDI: 001387e6 EBP: f5431f64 ESP: f5431f64
kernel: [ 2758.972245]  DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068
kernel: [ 2758.972247] CR0: 8005003b CR2: 60e453e0 CR3: 34fe5000 CR4: 000006d0
kernel: [ 2758.972249] DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000
kernel: [ 2758.972250] DR6: ffff0ff0 DR7: 00000403
kernel: [ 2758.972253]  [<c014e63b>] getnstimeofday+0x4b/0x100
kernel: [ 2758.972259]  [<c014e706>] do_gettimeofday+0x16/0x40
kernel: [ 2758.972262]  [<c0136f62>] sys_gettimeofday+0x22/0x70
kernel: [ 2758.972265]  [<c0103f7b>] sysenter_do_call+0x12/0x2f

Anyone seen that?  I guess the next step is for me to try using
the nv driver, just to see if it's the restricted driver.
- Dan