JSI Tip 2692. In 'Open With', I accidentally checked 'Always use this program to open these files'.

The solution to restore the Open With choice depends upon the operating system:

Windows NT 4.0

To restore the Open With choice on a right click, open a CMD prompt and type:

assoc .xxx=

where .xxx is the file extension.

NOTE: See tip 0482.

Windows 2000

Windows 2000 can support multiple Open With choices per file extension. The choices are configured per user, at the following key:

HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionExplorerFileExts

Each file extension that has an Open With choice has a .xxx sub-key. The .xxx sub-key has a OpenWithList sub-key, yielding the following registry path:

HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionExplorerFileExts.xxxOpenWithList

The OpenWithList sub-key has a string (REG_SZ) value name of MRULIST which contains a list of one character Value Names, one for each unique program. Here is an example of the .htm extension on my workstation:

HKCUSoftwareMicrosoftWindowsCurrentVersionExplorerFileExts.htmOpenWithList    a   REG_SZ  iexplore.exe    MRUList     REG_SZ  acfbehgd    b   REG_SZ  WINWORD.EXE    c   REG_SZ  notepad.exe    d   REG_SZ  Acrobat.exe    e   REG_SZ  FRONTPG.EXE    f   REG_SZ  agent.exe    g   REG_SZ  EXCEL.EXE    h   REG_SZ  POWERPNT.EXE

When deleting one of these one character value names, you must remove it from MRUList.  If you delete the last entry in the MRUList, delete the entire .xxx sub-key.

NOTE: The sequence of the characters in the MRULIST is the sequence of the apps you see in the Open With dialog.

NOTE: If you create a new .xxx sub-key by checking the Always use this program to open these files box, the .xxx sub-key receives an alphabetic character value name with a string of ProgramName.exe.

NOTE: If you hold down the shift key as you right-click a file, the Open with choice is added to the context menu.