Also facing this exact same issue, with vbox.

- Karmic/x86_64
- Dual-core Xeon 2.8 GHZ (in case it matters, for SMP locks...)
- virtualbox-3.1 (3.1.0-55467_Ubuntu_karmic)
- linux-image-2.6.31-16-generic (2.6.31-16.52)
- pulseaudio (1:0.9.19-0ubuntu4)

I get tons of the below:
[,,,]
Dec  9 11:35:41 tonarra pulseaudio[2143]: asyncq.c: q overrun, queuing locally
Dec  9 11:35:46 tonarra pulseaudio[2143]: ratelimit.c: 78084 events suppressed
Dec  9 11:35:51 tonarra pulseaudio[2143]: ratelimit.c: 156553 events suppressed
Dec  9 11:35:51 tonarra pulseaudio[2143]: asyncq.c: q overrun, queuing locally
Dec  9 11:35:51 tonarra pulseaudio[2143]: asyncq.c: q overrun, queuing locally
Dec  9 11:35:51 tonarra pulseaudio[2143]: asyncq.c: q overrun, queuing locally
Dec  9 11:35:51 tonarra pulseaudio[2143]: asyncq.c: q overrun, queuing locally
[...]

The pulseaudio process was taking 115% CPU (more than one core). Kill -15 did not stop it. Kill -9 produced the following OOPS (not sure it is related).

Dec  9 11:36:35 tonarra kernel: [88441.160129] wpa_supplican D 00000000ffffffff     0  1175      1 0x00000000
Dec  9 11:36:35 tonarra kernel: [88441.160140]  ffff88019ae15a38 0000000000000082 ffff88019ae159b8 0000000000015880
Dec  9 11:36:35 tonarra kernel: [88441.160151]  ffff8801b0cf1a60 0000000000015880 0000000000015880 0000000000015880
Dec  9 11:36:35 tonarra kernel: [88441.160160]  0000000000015880 ffff8801b0cf1a60 0000000000015880 0000000000015880
Dec  9 11:36:35 tonarra kernel: [88441.160170] Call Trace:
Dec  9 11:36:35 tonarra kernel: [88441.160189]  [<ffffffff815286b7>] __mutex_lock_slowpath+0xd7/0x160
Dec  9 11:36:35 tonarra kernel: [88441.160200]  [<ffffffff8142a241>] ? sock_alloc_send_pskb+0x1c1/0x310
Dec  9 11:36:35 tonarra kernel: [88441.160208]  [<ffffffff815285b6>] mutex_lock+0x26/0x50
Dec  9 11:36:35 tonarra kernel: [88441.160250]  [<ffffffffa0b4ecc5>] iwl_mac_config+0x35/0x2a0 [iwlcore]
Dec  9 11:36:35 tonarra kernel: [88441.160261]  [<ffffffff81045d09>] ? __wake_up_common+0x59/0x90
Dec  9 11:36:35 tonarra kernel: [88441.160293]  [<ffffffffa00f6af5>] ieee80211_hw_config+0x85/0xd0 [mac80211]
Dec  9 11:36:35 tonarra kernel: [88441.160323]  [<ffffffffa0103199>] ieee80211_recalc_idle+0x49/0x60 [mac80211]
Dec  9 11:36:35 tonarra kernel: [88441.160351]  [<ffffffffa00fb80d>] __ieee80211_start_scan+0xad/0x230 [mac80211]
Dec  9 11:36:35 tonarra kernel: [88441.160379]  [<ffffffffa00fba85>] ieee80211_request_scan+0x35/0x60 [mac80211]
Dec  9 11:36:35 tonarra kernel: [88441.160408]  [<ffffffffa01072b0>] ieee80211_scan+0x60/0x70 [mac80211]
Dec  9 11:36:35 tonarra kernel: [88441.160436]  [<ffffffffa00c94db>] cfg80211_wext_siwscan+0x18b/0x210 [cfg80211]
Dec  9 11:36:35 tonarra kernel: [88441.160446]  [<ffffffff8150a89c>] ioctl_standard_iw_point+0x1bc/0x370
Dec  9 11:36:35 tonarra kernel: [88441.160468]  [<ffffffffa00c9350>] ? cfg80211_wext_siwscan+0x0/0x210 [cfg80211]
Dec  9 11:36:35 tonarra kernel: [88441.160477]  [<ffffffff8150aa50>] ? ioctl_standard_call+0x0/0xd0
Dec  9 11:36:35 tonarra kernel: [88441.160485]  [<ffffffff81509ac0>] ? ioctl_private_call+0x0/0xa0
Dec  9 11:36:35 tonarra kernel: [88441.160492]  [<ffffffff8150ab01>] ioctl_standard_call+0xb1/0xd0
Dec  9 11:36:35 tonarra kernel: [88441.160501]  [<ffffffff81438f40>] ? __dev_get_by_name+0xa0/0xc0
Dec  9 11:36:35 tonarra kernel: [88441.160509]  [<ffffffff8150aa50>] ? ioctl_standard_call+0x0/0xd0
Dec  9 11:36:35 tonarra kernel: [88441.160517]  [<ffffffff81509c49>] wireless_process_ioctl+0xd9/0x160
Dec  9 11:36:35 tonarra kernel: [88441.160524]  [<ffffffff8150aa50>] ? ioctl_standard_call+0x0/0xd0
Dec  9 11:36:35 tonarra kernel: [88441.160532]  [<ffffffff81509d3c>] wext_ioctl_dispatch+0x6c/0xb0
Dec  9 11:36:35 tonarra kernel: [88441.160539]  [<ffffffff81509ac0>] ? ioctl_private_call+0x0/0xa0
Dec  9 11:36:35 tonarra kernel: [88441.160547]  [<ffffffff81509eb1>] wext_handle_ioctl+0x41/0x90
Dec  9 11:36:35 tonarra kernel: [88441.160555]  [<ffffffff81439fde>] dev_ioctl+0x27e/0x290
Dec  9 11:36:35 tonarra kernel: [88441.160563]  [<ffffffff81427155>] sock_ioctl+0x95/0x280
Dec  9 11:36:35 tonarra kernel: [88441.160572]  [<ffffffff8112e36d>] vfs_ioctl+0x1d/0xa0
Dec  9 11:36:35 tonarra kernel: [88441.160579]  [<ffffffff8112e999>] do_vfs_ioctl+0x79/0x370
Dec  9 11:36:35 tonarra kernel: [88441.160586]  [<ffffffff8112ed11>] sys_ioctl+0x81/0xa0
Dec  9 11:36:35 tonarra kernel: [88441.160596]  [<ffffffff81012002>] system_call_fastpath+0x16/0x1b
Dec  9 11:36:35 tonarra kernel: [88441.160646] firefox       D 00000000ffffffff     0  7323      1 0x00000000
Dec  9 11:36:35 tonarra kernel: [88441.160656]  ffff880183545ae8 0000000000000082 0000000000000000 0000000000015880
Dec  9 11:36:35 tonarra kernel: [88441.160666]  ffff8801669183b0 0000000000015880 0000000000015880 0000000000015880
Dec  9 11:36:35 tonarra kernel: [88441.160675]  0000000000015880 ffff8801669183b0 0000000000015880 0000000000015880
Dec  9 11:36:35 tonarra kernel: [88441.160684] Call Trace:
Dec  9 11:36:35 tonarra kernel: [88441.160693]  [<ffffffff815286b7>] __mutex_lock_slowpath+0xd7/0x160
Dec  9 11:36:35 tonarra kernel: [88441.160701]  [<ffffffff815285b6>] mutex_lock+0x26/0x50
Dec  9 11:36:35 tonarra kernel: [88441.160710]  [<ffffffff81443f80>] rtnl_lock+0x10/0x20
Dec  9 11:36:35 tonarra kernel: [88441.160717]  [<ffffffff81443fa1>] rtnetlink_rcv+0x11/0x30
Dec  9 11:36:35 tonarra kernel: [88441.160725]  [<ffffffff81459855>] netlink_unicast+0x2c5/0x2e0
Dec  9 11:36:35 tonarra kernel: [88441.160732]  [<ffffffff8145ab50>] netlink_sendmsg+0x220/0x300
Dec  9 11:36:35 tonarra kernel: [88441.160741]  [<ffffffff81426ea6>] sock_sendmsg+0x106/0x130
Dec  9 11:36:35 tonarra kernel: [88441.160750]  [<ffffffff81529a59>] ? _spin_lock+0x9/0x10
Dec  9 11:36:35 tonarra kernel: [88441.160760]  [<ffffffff81078b30>] ? autoremove_wake_function+0x0/0x40
Dec  9 11:36:35 tonarra kernel: [88441.160770]  [<ffffffff81036419>] ? default_spin_lock_flags+0x9/0x10
Dec  9 11:36:35 tonarra kernel: [88441.160780]  [<ffffffff8104a87e>] ? __wake_up+0x4e/0x70
Dec  9 11:36:35 tonarra kernel: [88441.160790]  [<ffffffff8145803e>] ? netlink_table_ungrab+0x2e/0x30
Dec  9 11:36:35 tonarra kernel: [88441.160797]  [<ffffffff8145a6b9>] ? netlink_insert+0x89/0x150
Dec  9 11:36:35 tonarra kernel: [88441.160805]  [<ffffffff814274f0>] sys_sendto+0x120/0x180
Dec  9 11:36:35 tonarra kernel: [88441.160813]  [<ffffffff81425f67>] ? sock_map_fd+0x47/0x70
Dec  9 11:36:35 tonarra kernel: [88441.160822]  [<ffffffff81012002>] system_call_fastpath+0x16/0x1b