Help - cannot start any executable on Windows!

Last week, we had the problem, that we suddenly couldn't start any executable "xxx.exe" on Windows 2000 - what's happend ?

If you open the menu "Tools->Folder Options" in the Windows 2000 explorer you can add a global file type association for .EXE ( Please don't do it ! ). Well, we haven't read this article and we have done it. We have associated the Windows Shell (Cmd.exe) to .EXE; after this, each executable opens the Windows Shell - really not what we want. Well, we deleted this association again, and from this point, it was not possible to start an executable, instead the well known box to select an application opens - the whole Windows 2000 becomes unusable!

By default, exe and .exe file extensions cannot be used in Windows because they are reserved for running programs. However, the extension *.exe can be used as a valid file extension when creating a new application association. If you create an association with the *.exe extension, you will no longer be able to run applications or programs !

In Microsoft Windows NT 4.0, all entries specific to file type associations are stored in the following registry key:

HKEY_LOCAL_MACHINE\SOFTWARE\Classes

In Windows 2000, a new location is added for storage of user-specific file type associations in the following registry key:

HKEY_CURRENT_USER\SOFTWARE\Classes

This location allows for unique customization of file type associations in the user's profile, without having to duplicate information in multiple registry locations and unnecessarily increase the registry size.

However In Windows 2000, information stored in the ....

HKEY_LOCAL_MACHINE\SOFTWARE\Classes

.... registry key still contains global file type associations that are global to all users of the computer.

However, entries that reside in the ....

HKEY_CURRENT_USER\SOFTWARE\Classes

.... registry key take precedence in the event of a duplication. The user interface (UI) still points to the global settings in the ....

HKEY_LOCAL_MACHINE\SOFTWARE\Classes

.... registry key. In addition, security is changed so that only members of the Administrators or Power Users group have permissions to this dialog box. This affects workstations, servers, and servers in Remote Administration mode.

Start another Windows 2000 machine which is working properly.

Mount a Share from the unusable Windows 2000 to the working one. You can do this as an administrator (e.g. \\machine\c$).

Export the following registry key from the working machine using the import utility in the registry editor (Regedit.exe) ....

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\.exe

... to a file ( with the extension .reg ) which is located on the mounted Share.

Double click on this saved file on the unusable machine. Fortunately this file has an extension .REG, so you can install this saved registry key on the unusable machine. A box opens, confirm the message. Now, the .EXE registry key is restored and all .EXEs will work again.

We suggest to backup the whole registry using the export tool in the registry editor (Regedit.exe).