This trick is useful for anyone who wants to stop specific applications from running without having to install any software of any kind, all they need to do is make a simple edit in the registry.
Open your registry and find the key [HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion \Policies\Explorer]
Create a new DWORD value and name it "DisallowRun" set the value to "1" to enable application restrictions or "0" to allow all applications to run.
Then create a new sub-key called [HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion \Policies\Explorer\DisallowRun] and define the applications the are to be restricted. Creating a new string value for each application, named as consecutive numbers, and setting the value to the filename to be restricted (e.g. "regedit.exe").
Restart Windows for the changes to take effect.
More in: How To: Restrict Users From Running Specific Windows Programs