Do you already have Java installed? If so, are you trying to install the new version to the old directory? If anything is running that uses Java, then you will get this message. You will either have to install the new version to a new directory or remove the old version first.
And it does not name the file that it can't access? Might the event log have more information? Control Panel - Administrative Tools - Event Viewer - probably the Application tab. I'm grasping at straws here.