I've the same problem with a INTEL P55 Mainboard. Very sad its a productive machine.
I get it randomly all 2-4 weeks on one VM of 6. Always "cpu stuck" and the websites on it are down. I hate it very badly.

Host:  2.6.32-24-server #41-Ubuntu (now installing #42)
VM: 2.6.32-24-server #41-Ubuntu (now installing #42)

syslog crashed VM:
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Sep  6 08:47:51 cluster qmail-smtpd: qmail-smtpd/VC started
Sep  6 08:49:03 cluster kernel: [538123.970006] BUG: soft lockup - CPU#0 stuck for 61s! [swapper:0]
Sep  6 08:49:03 cluster kernel: [538123.993618] Modules linked in: fbcon psmouse tileblit font bitblit i2c_piix4 serio_raw softcursor lp vga16fb vgastate parport floppy
Sep  6 08:49:03 cluster kernel: [538123.993618] CPU 0:
Sep  6 08:49:03 cluster kernel: [538123.993618] Modules linked in: fbcon psmouse tileblit font bitblit i2c_piix4 serio_raw softcursor lp vga16fb vgastate parport floppy
Sep  6 08:49:03 cluster kernel: [538123.993618] Pid: 0, comm: swapper Not tainted 2.6.32-24-server #41-Ubuntu Bochs
Sep  6 08:49:03 cluster kernel: [538123.993618] RIP: 0010:[<ffffffff814abd6b>]  [<ffffffff814abd6b>] __inet_lookup_established+0x1ab/0x2c0
Sep  6 08:49:03 cluster kernel: [538123.993618] RSP: 0018:ffff880001c03ba0  EFLAGS: 00000202
Sep  6 08:49:03 cluster kernel: [538123.993618] RAX: 000000000001cb93 RBX: ffff880001c03be0 RCX: 0000000091a53275
Sep  6 08:49:03 cluster kernel: [538123.993618] RDX: ffffc900002c8cb0 RSI: ffffffff81a49000 RDI: 000000000001cb93
Sep  6 08:49:03 cluster kernel: [538123.993618] RBP: ffffffff81013cb3 R08: 00000000e3a9806b R09: 0000000000509bf3
Sep  6 08:49:03 cluster kernel: [538123.993618] R10: 0000000000000002 R11: 0000000000000002 R12: ffff880001c03b20
Sep  6 08:49:03 cluster kernel: [538123.993618] R13: 46c0c8c363174858 R14: ffffffff81a46d80 R15: ffffffff8155fe2c
Sep  6 08:49:03 cluster kernel: [538123.993618] FS:  0000000000000000(0000) GS:ffff880001c00000(0000) knlGS:0000000000000000
Sep  6 08:49:03 cluster kernel: [538123.993618] CS:  0010 DS: 0018 ES: 0018 CR0: 000000008005003b
Sep  6 08:49:03 cluster kernel: [538123.993618] CR2: 00000000f7056000 CR3: 00000000199f1000 CR4: 00000000000006f0
Sep  6 08:49:03 cluster kernel: [538123.993618] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
Sep  6 08:49:03 cluster kernel: [538123.993618] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Sep  6 08:49:03 cluster kernel: [538123.993618] Call Trace:
Sep  6 08:49:03 cluster kernel: [538123.993618]  <IRQ>  [<ffffffff8146d35d>] ? __skb_checksum_complete_head+0x1d/0x70
Sep  6 08:49:03 cluster kernel: [538123.993618]  [<ffffffff814c48bf>] ? tcp_v4_rcv+0x1cf/0x7e0
Sep  6 08:49:03 cluster kernel: [538123.993618]  [<ffffffff8146906e>] ? consume_skb+0x1e/0x40
Sep  6 08:49:03 cluster kernel: [538123.993618]  [<ffffffff814a2cdd>] ? ip_local_deliver_finish+0xdd/0x2d0
Sep  6 08:49:03 cluster kernel: [538123.993618]  [<ffffffff814a2f60>] ? ip_local_deliver+0x90/0xa0
Sep  6 08:49:03 cluster kernel: [538123.993618]  [<ffffffff814a241d>] ? ip_rcv_finish+0x12d/0x440
Sep  6 08:49:03 cluster kernel: [538123.993618]  [<ffffffff814a29a5>] ? ip_rcv+0x275/0x360
Sep  6 08:49:03 cluster kernel: [538123.993618]  [<ffffffff8147319a>] ? netif_receive_skb+0x38a/0x5d0
Sep  6 08:49:03 cluster kernel: [538123.993618]  [<ffffffff813db303>] ? receive_skb+0x503/0x580
Sep  6 08:49:03 cluster kernel: [538123.993618]  [<ffffffff813db9ca>] ? virtnet_poll+0xea/0x160
Sep  6 08:49:03 cluster kernel: [538123.993618]  [<ffffffff81094218>] ? tick_dev_program_event+0x68/0xd0
Sep  6 08:49:03 cluster kernel: [538123.993618]  [<ffffffff810397a9>] ? default_spin_lock_flags+0x9/0x10
Sep  6 08:49:03 cluster kernel: [538123.993618]  [<ffffffff81473c8f>] ? net_rx_action+0x10f/0x250
Sep  6 08:49:03 cluster kernel: [538123.993618]  [<ffffffff8106e2f7>] ? __do_softirq+0xb7/0x1e0
Sep  6 08:4Sep  6 09:38:21 cluster kernel: imklog 4.2.0, log source = /proc/kmsg started.
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