In the latest release of MySQL Workbench (5.2.35), we received a number of reports that some people upgrading over a previous installation ended up in not being able to launch MySQL Workbench afterwards, instead receiving an error such as Access to the path ‘C:\Program Files (x86)\MySQL\MySQL Workbench CE 5.2.35\db_utils.pyc’ is denied. The cause for that seems to be a problem with access privileges on files that are created when Workbench is run. If you run into that problem, a possible workaround should be to start Workbench with elevated privileges one time. To do this, right-click the Workbench application icon in your startmenu and select “Run as administrator”. Please leave a comment whether this workaround solves the reported problem for you.
UPDATE: A new 220.127.116.11 msi package has been uploaded, which resolves this issue. You can download it from the usual location.