OS X Host panic

[digititus]

I have Virtualbox 4.2.4 installed on OS X server 10.7.5 host. I have one VM running (Ubuntu 12.0.4 LTS), headless mode. I have had the system running for approximately 1 month. I have had 3 panics in this time where I have had to power cycle the host. Console log has many of the following errors:

Nov 19 00:51:25 mail kernel[0]: aio_queue_async_request(): too many in flight for proc: 16.
Nov 19 00:57:00 mail kernel[0]: aio_queue_async_request(): too many in flight for proc: 16.
Nov 19 01:20:33 mail kernel[0]: aio_queue_async_request(): too many in flight for proc: 16.
Nov 19 02:39:51 mail kernel[0]: aio_queue_async_request(): too many in flight for proc: 16.
Nov 19 05:47:14 mail kernel[0]: aio_queue_async_request(): too many in flight for proc: 16.
Nov 19 06:08:30 mail kernel[0]: aio_queue_async_request(): too many in flight for proc: 16.
Nov 19 06:09:06 mail kernel[0]: aio_queue_async_request(): too many in flight for proc: 16.
Nov 19 07:07:31 mail kernel[0]: aio_queue_async_request(): too many in flight for proc: 16.
Nov 19 07:36:31 mail kernel[0]: aio_queue_async_request(): too many in flight for proc: 16.
Nov 19 07:39:01 mail kernel[0]: aio_queue_async_request(): too many in flight for proc: 16.
Nov 19 07:44:07 mail kernel[0]: aio_queue_async_request(): too many in flight for proc: 16.

I have never seen these errors on this server before and the only new software is VBox. The server has been very stable up until this point. Any help finding the cause of this appreciated.