On the way to work this morning, I saw an email from bhearsum.

Turns out the latest update from VMware (ESX 3.5 update2) contained a licensing bug. Starting at 00:01 on 12th August (yes, today!), the licensing software would incorrectly think that VMWare licenses had expired. Any running VMs would stay running. However, any VMs being powered up, restarted or moved would refuse to start; instead it would throw an “Internal Error” and remain down.
More details from VMware, and selected press coverage, are here:

• http://kb.vmware.com/selfservice/microsites/search.do?cmd=displayKC&docType=kc&externalId=1006716&sliceId=1&docTypeID=DT_KB_1_1&dialogID=21564262&stateId=1%200%2021562443
• http://www.theregister.co.uk/2008/08/12/vmware_12_august_esx_cockup/
• http://www.computerworld.com/action/article.do?command=viewArticleBasic&articleId=9112439&intsrc=hm_list
• http://www.infoworld.com/article/08/08/12/VMware_licensing_bug_blacks_out_virtual_servers_1.html

Thankfully, we had not installed that latest update from VMware, so we dodged that bullet by sheer luck.

(Today could have been a *lot* more exciting!)