It turned out that when I’d try to use the open with context menu in windows explorer, it would open the file with notepad by default, instead of showing the actual open with window.
A little registry hacking is required to restore the default behaviour.
Steps:
- Open the registry editor and navigate to HKEY_CLASSES_ROOT\Unknown\shell
- There should be a sub-key called openas\command. If that doesn’t exist, create it.
- The “default” entry in HKEY_CLASSES_ROOT\Unknown\shell\openas\command should be a string type. It is the expandable string type in my Windows XP installation. The value should be
%SystemRoot%\system32\rundll32.exe %SystemRoot%\system32\shell32.dll,OpenAs_RunDLL %1
- Navigate back to the HKEY_CLASSES_ROOT\Unknown\shell
- The “default” entry for this key should be “openas”
These steps should fix the issue and restore the default behaviour.