The installation is failing due to permissions errors on several files. These permissions errors are preventing Flash Player from correctly uninstalling files from previous versions and then installing the new version. There are various reasons this happens, and could be due to anti-virus software or some other software. Please review this Microsoft kb article -us/kb/968003 and run SubInAcl to reset the permissions on the file system and registry. You should be able to install Flash Player afterwards. I would perform tasks in the following order: