Hi,  the frequency of this problem has been reduced significantly since I installed kvm-source, however, it has not been completely eliminated.

kvm                                        1:84+dfsg-0ubuntu11
kvm-source                                 1:84+dfsg-0ubuntu11
linux-image-2.6.28-11-generic              2.6.28-11.42

Apr 23 22:20:57 aethereal kernel: [19380.467724] wlan0: associated
Apr 23 22:26:40 aethereal kernel: [19723.700129] ------------[ cut here ]------------
Apr 23 22:26:40 aethereal kernel: [19723.700135] kernel BUG at /var/lib/dkms/kvm/84/build/x86/mmu.c:684!
Apr 23 22:26:40 aethereal kernel: [19723.700137] invalid opcode: 0000 [#1] SMP
Apr 23 22:26:40 aethereal kernel: [19723.700140] last sysfs file: /sys/devices/pci0000:00/0000:00:1c.1/0000:0c:00.0/rfkill/rfkill0/state
Apr 23 22:26:40 aethereal kernel: [19723.700143] Dumping ftrace buffer:
Apr 23 22:26:40 aethereal kernel: [19723.700146]    (ftrace buffer empty)
Apr 23 22:26:40 aethereal kernel: [19723.700147] CPU 0
Apr 23 22:26:40 aethereal kernel: [19723.700149] Modules linked in: binfmt_misci915 drm ppdev bridge stp bnep input_polldev kvm_intel kvm snd_hwdep sbp2 lp parport snd_hda_intel snd_pcm_oss snd_mixer_oss snd_pcm snd_seq_dummy arc4 snd_seq_oss ecb snd_seq_midi pata_pcmcia snd_rawmidi snd_seq_midi_event iwlagn iwlcore snd_seq snd_timer snd_seq_device led_class snd pcmcia mac80211 soundcore yenta_socket rsrc_nonstatic pcmcia_core dcdbas iTCO_wdt iTCO_vendor_support psmouse btusb snd_page_alloc cfg80211 pcspkr serio_raw joydev sha256_generic aes_x86_64 aes_generic cbc dm_crypt fbcon tileblit font bitblit softcursor squashfs unionfs nls_iso8859_1 nls_cp437 vfat fat usbhid usb_storage ohci1394 ieee1394 tg3 video output intel_agp
Apr 23 22:26:40 aethereal kernel: [19723.700189] Pid: 10015, comm: kvm Tainted:G        W  2.6.28-11-generic #42-Ubuntu
Apr 23 22:26:40 aethereal kernel: [19723.700191] RIP: 0010:[<ffffffffa03e7cd5>] [<ffffffffa03e7cd5>] rmap_write_protect+0x325/0x340 [kvm]
Apr 23 22:26:40 aethereal kernel: [19723.700207] RSP: 0018:ffff8800b5023a38  EFLAGS: 00010246
Apr 23 22:26:40 aethereal kernel: [19723.700209] RAX: ffffc20014d971f0 RBX: 000000000001493e RCX: ffff88011dc3f030
Apr 23 22:26:40 aethereal kernel: [19723.700210] RDX: 00000000edbfa63e RSI: 09bf570aedbfa63e RDI: ffff88005992dc30
Apr 23 22:26:40 aethereal kernel: [19723.700212] RBP: ffff8800b5023a58 R08: ffff880059c2f0a0 R09: ffff88005b3f8001
Apr 23 22:26:40 aethereal kernel: [19723.700213] R10: 0000000000000002 R11: 0000000000000000 R12: 0000000000000001
Apr 23 22:26:40 aethereal kernel: [19723.700215] R13: ffff88005dd48840 R14: ffff8800b5028000 R15: ffff88005d0b8000
Apr 23 22:26:40 aethereal kernel: [19723.700217] FS:  00007f28bcb21950(0000) GS:ffffffff80aa3000(0000) knlGS:0000000000000000
Apr 23 22:26:40 aethereal kernel: [19723.700219] CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
Apr 23 22:26:40 aethereal kernel: [19723.700220] CR2: 0000000007c6d38c CR3: 000000005dcfe000 CR4: 00000000000026a0
Apr 23 22:26:40 aethereal kernel: [19723.700222] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
Apr 23 22:26:40 aethereal kernel: [19723.700223] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Apr 23 22:26:40 aethereal kernel: [19723.700225] Process kvm (pid: 10015, threadinfo ffff8800b5022000, task ffff88002518c320)
Apr 23 22:26:40 aethereal kernel: [19723.700227] Stack:
Apr 23 22:26:40 aethereal kernel: [19723.700228]  0000000000000001 0000000000000000 ffff88005dd48840 ffff88005dd48840
Apr 23 22:26:40 aethereal kernel: [19723.700231]  ffff8800b5023ab8 ffffffffa03e8286 ffff8800b5028000 000000000000029a
Apr 23 22:26:40 aethereal kernel: [19723.700234]  000000005d0b8000 000000000001493e ffff8800b5028000 0000000000000001
Apr 23 22:26:40 aethereal kernel: [19723.700238] Call Trace:
Apr 23 22:26:40 aethereal kernel: [19723.700240]  [<ffffffffa03e8286>] kvm_mmu_get_page+0x416/0x460 [kvm]
Apr 23 22:26:40 aethereal kernel: [19723.700248]  [<ffffffffa03ea890>] paging64_page_fault+0x280/0x510 [kvm]
Apr 23 22:26:40 aethereal kernel: [19723.700257]  [<ffffffffa03e8bba>] kvm_mmu_page_fault+0x1a/0xb0 [kvm]
Apr 23 22:26:40 aethereal kernel: [19723.700265]  [<ffffffffa0410297>] handle_exception+0x377/0x420 [kvm_intel]
Apr 23 22:26:40 aethereal kernel: [19723.700272]  [<ffffffffa040ec91>] kvm_handle_exit+0x121/0x2e0 [kvm_intel]
Apr 23 22:26:40 aethereal kernel: [19723.700276]  [<ffffffffa03e43ec>] kvm_arch_vcpu_ioctl_run+0x69c/0xbd0 [kvm]
Apr 23 22:26:40 aethereal kernel: [19723.700285]  [<ffffffff80277ce9>] ? futex_wait+0x379/0x4b0
Apr 23 22:26:40 aethereal kernel: [19723.700291]  [<ffffffff8023ec1a>] ? __wake_up_common+0x5a/0x90
Apr 23 22:26:40 aethereal kernel: [19723.700295]  [<ffffffffa03d96a2>] kvm_vcpu_ioctl+0x2e2/0x5a0 [kvm]
Apr 23 22:26:40 aethereal kernel: [19723.700303]  [<ffffffff8069e569>] ? _spin_lock+0x9/0x10
Apr 23 22:26:40 aethereal kernel: [19723.700307]  [<ffffffff80277718>] ? futex_wake+0xf8/0x130
Apr 23 22:26:40 aethereal kernel: [19723.700309]  [<ffffffff802f62d1>] vfs_ioctl+0x31/0xa0
Apr 23 22:26:40 aethereal kernel: [19723.700313]  [<ffffffff802f6685>] do_vfs_ioctl+0x75/0x230
Apr 23 22:26:40 aethereal kernel: [19723.700315]  [<ffffffff802f68d9>] sys_ioctl+0x99/0xa0
Apr 23 22:26:40 aethereal kernel: [19723.700318]  [<ffffffff8021253a>] system_call_fastpath+0x16/0x1b
Apr 23 22:26:40 aethereal kernel: [19723.700321] Code: 48 8b 76 20 48 85 f6 75 cd e9 45 fd ff ff 0f 1f 84 00 00 00 00 00 48 8b 76 20 48 89 d1 48 85 f6 75 b4 0f1f 40 00 e9 28 fd ff ff <0f> 0b eb fe 0f 1f 80 00 00 00 00 0f 0b eb fe 0f 1f 4000 0f 0b
Apr 23 22:26:40 aethereal kernel: [19723.700348] RIP  [<ffffffffa03e7cd5>] rmap_write_protect+0x325/0x340 [kvm]
Apr 23 22:26:40 aethereal kernel: [19723.700356]  RSP <ffff8800b5023a38>
Apr 23 22:26:40 aethereal kernel: [19723.700359] ---[ end trace c637ce30457bf64b ]---