6.0.0m70 upgrade via windows installer failed

This morning I attempted to upgrade Confluence on Windows from 6.0.0-m68 to 6.0.0-m70

I've been upgrading this Confluence with all the milestones using the windows installer.

This time I got an error that was something like 'file still in use', the installer didn't complete, and I was left with most of my install directory empty.

I've attached my application log. All that is left in my installation directory is Logs directory (Catalina logs etc are gone though), and the confluence\WEB-INF\lib and the JRE directory.

We should confirm this isn't a freaky one off.

See also https://jira.atlassian.com/browse/CONF-43948