"Sometimes when you fill a vacuum, it still sucks."
Windows Media Player is reported to break on playing MP4 files.
The sfc (Resource Checker), a tool that scans the integrity of all protected system files and replaces incorrect versions with correct Microsoft versions, chokes on jscript.dll with altered permissions.
Printing to “Microsoft Print to PDF” is reported to break.
Proxy automatic configuration scripts (PAC scripts) may not work.