I have experienced apparently the same hang-up today with kernel 3.5.0-22 of KUbuntu 12.10
I must note it happened previously from time to time, but I assumed this is some hardware issue
until I looked in the linux logs.
The relevant part of the ``syslog'' file looks like:

Jan 21 17:33:27 Eridanus kernel: [957585.389930] ------------[ cut here ]------------
Jan 21 17:33:27 Eridanus kernel: [957585.389939] WARNING: at /build/buildd/linux-3.5.0/kernel/watchdog.c:242 watchdog_overflow_callback+0x9a/0xc0()
Jan 21 17:33:27 Eridanus kernel: [957585.389941] Hardware name: To be filled by O.E.M.
Jan 21 17:33:27 Eridanus kernel: [957585.389942] Watchdog detected hard LOCKUP on cpu 4
Jan 21 17:33:27 Eridanus kernel: [957585.389943] Modules linked in: xt_recent btrfs zlib_deflate libcrc32c ufs qnx4 hfsplus hfs minix ntfs msdos jfs xfs reiserfs ext2 parport_pc ppdev bnep rfcomm bluetooth binfmt_misc nls_iso8859_1 snd_hda_codec_hdmi ip6t_REJECT xt_hl ip6t_rt nf_conntrack_ipv6 nf_defrag_ipv6 ipt_REJECT xt_LOG xt_limit xt_tcpudp xt_addrtype arc4 xt_state ip6table_filter ip6_tables nf_conntrack_netbios_ns eeepc_wmi asus_wmi mxm_wmi sparse_keymap nf_conntrack_broadcast nf_nat_ftp nf_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_conntrack_ftp nf_conntrack iptable_filter ip_tables kvm_amd x_tables kvm ghash_clmulni_intel aesni_intel cryptd aes_x86_64 snd_hda_codec_realtek psmouse edac_core edac_mce_amd serio_raw snd_seq_midi k10temp fam15h_power snd_rawmidi snd_hda_intel snd_hda_codec snd_seq_midi_event snd_hwdep rtl8192ce rtl8192c_common snd_seq rtlwifi snd_pcm nvidia(PO) snd_seq_device mac80211 snd_timer sp5100_tco snd i2c_piix4 cfg80211 soundcore snd_page_alloc wmi mac_hid it87 hwmon_vid lp parport 
uas us
Jan 21 17:33:27 Eridanus kernel: b_storage hid_generic microcode r8169 usbhid hid
Jan 21 17:33:27 Eridanus kernel: [957585.390004] Pid: 1517, comm: wpa_supplicant Tainted: P        W  O 3.5.0-21-generic #32-Ubuntu
Jan 21 17:33:27 Eridanus kernel: [957585.390005] Call Trace:
Jan 21 17:33:27 Eridanus kernel: [957585.390006]  <NMI>  [<ffffffff81051c1f>] warn_slowpath_common+0x7f/0xc0
Jan 21 17:33:27 Eridanus kernel: [957585.390015]  [<ffffffff81051d16>] warn_slowpath_fmt+0x46/0x50
Jan 21 17:33:27 Eridanus kernel: [957585.390018]  [<ffffffff8108a255>] ? sched_clock_cpu+0xc5/0x120
Jan 21 17:33:27 Eridanus kernel: [957585.390021]  [<ffffffff810de320>] ? touch_nmi_watchdog+0x80/0x80
Jan 21 17:33:27 Eridanus kernel: [957585.390024]  [<ffffffff810de3ba>] watchdog_overflow_callback+0x9a/0xc0
Jan 21 17:33:27 Eridanus kernel: [957585.390028]  [<ffffffff8111a63d>] __perf_event_overflow+0x9d/0x230
Jan 21 17:33:27 Eridanus kernel: [957585.390030]  [<ffffffff81117b04>] ? perf_event_update_userpage+0x24/0x110
Jan 21 17:33:27 Eridanus kernel: [957585.390033]  [<ffffffff8111b154>] perf_event_overflow+0x14/0x20
Jan 21 17:33:27 Eridanus kernel: [957585.390037]  [<ffffffff81024643>] x86_pmu_handle_irq+0xe3/0x130
Jan 21 17:33:27 Eridanus kernel: [957585.390041]  [<ffffffff8168539d>] perf_event_nmi_handler+0x1d/0x20
Jan 21 17:33:27 Eridanus kernel: [957585.390043]  [<ffffffff81684b41>] nmi_handle.isra.0+0x51/0x80
Jan 21 17:33:27 Eridanus kernel: [957585.390142]  [<ffffffffa0746a20>] ? os_registry_init+0x290/0x290 [nvidia]
Jan 21 17:33:27 Eridanus kernel: [957585.390145]  [<ffffffff81684cf9>] do_nmi+0x189/0x360
Jan 21 17:33:27 EJan 21 17:37:23 Eridanus kernel: imklog 5.8.6, log source = /proc/kmsg started.

I believe it is very simular to what was reported here.