"soft lockup" in kernel

Dear community

Twice today our PG 9.1 server has caused a "soft lockup", with a kernel
message like this:

[1813775.496127] BUG: soft lockup - CPU#3 stuck for 73s! [postgres:18723]

Full dmesg output - http://pastebin.com/YdWSmNUp

The incidents were approximately two hours apart and the server was
momentarily unavailable before coming back again, with no restore actions
required - it just carried on. It's never done this before, I've checked
in the logs. The server is about 3 weeks old and runs Debian 7 under
VMWare.

Does anybody know what could cause this, and, if so, is it something to be
concerned about and what can be done to stop it?

Any help greatly appreciated.

Stuart

This email and any attachments contain confidential and proprietary information of Glide Utilities Limited intended only for the use of the person to whom it is addressed. Unauthorised disclosure, copying or distribution of the email or its content may result in legal liability. If you have received the email in error, please immediately notify us by telephone on +44 333 666 5555 or email glide(at)glide(dot)uk(dot)com

The sender does not accept liability for any loss or damage from receipt or use thereof which arises as a result of internet transmission. Any views/opinions expressed within this email and any attachments are that of the individual and not necessarily that of Glide Utilities Limited.

Glide is a registered trademark of Glide Utilities Limited. Registered Office: Alpha Tower, Suffolk Street Queensway, Birmingham, B1 1TT. Registered in England & Wales. Registered Company No. 06194523.