Correct conflicting Windows file associations

Windows uses a clever system to ensure files are recognised by the program that created them, so it can use the same application to open them again for viewing, editing or playback.

The system is called file association and when a computer is brand new the method works a treat. Unfortunately, as more and more programs are installed, some of them start to fight over which of them ‘owns’ a particular type of file, and when there are conflicts it soon becomes apparent to the user.

For example, after double-clicking a file to open it, a program other than the expected one might appear. Eagle-eyed users might also notice that in Windows Explorer a different style of icon appears next to the file’s name.

On these two pages we take a look at how users of Windows XP and Windows Vista can take control of errant file associations and play matchmaker by re-attaching files to their rightful programs.

The mechanism by which both Windows and people identify which program owns a particular file is the file extension. This is an extra bit of information tacked onto a file’s name but separated from the main part by a full stop; so we have examples such as ‘Revolution.mp3’ (a music file), ‘Holiday.doc’ (a Microsoft Word document) and ‘Dark Knight Trailer.avi’ (a movie clip).

Programs and parts of programs have file extensions too, the most common being .exe and .com. For historical reasons – and because it makes them easier to handle – most file extensions have three letters, but there’s nothing to stop them having more.

Where are all my file extensions?
Apart from putting the shut down button on the Start menu, the craziest decision Microsoft made when designing Windows was to hide many of the file extensions from Windows users. If you can’t see the file extensions when viewing folders you should turn them on and leave them on: they make file management much easier.

Do this in Windows XP by starting Windows Explorer (press Ctrl and E) opening the Tools menu and selecting Folder Options. When the Folder Options dialogue box appears, select the View tab and look under Advanced settings. Remove the tick from Hide extensions for known file types, and then click OK.

In Windows Vista, start Windows Explorer and click the Organize link on the left of the toolbar. Click Folder and Search Options, and when the Folder Options dialogue box appears click the View tab. In the Advanced settings section remove the tick from ‘Hide extensions for known file types’, and then click OK.