Sharepoint - An update conflict has occurred, and you must re-try this action.

I got this error today on a restored MOSS installation, when trying to add an existing content database:

An update conflict has occurred, and you must re-try this action. The object SPWebApplication Name=WEBAPPLICATIONNAME Parent=SPWebService is being updated by DOMAIN\USER, in the w3wp process, on machine SERVERNAME. View the tracing log for more information about the conflict.

I found this KB to solve this issue: http://support.microsoft.com/kb/939308

"This issue occurs if the contents of the file system cache on the front-end servers are newer than the contents of the configuration database. After you perform a system recovery, you may have to manually clear the file system cache on the local server."