Did you upgrade from Windows XP to Windows Vista? Do you turn off Explorer’s “Hide Known File Types” option?
If so, try this:
Right-click on your desktop, select “New” and then “Text File”.
Name your text file “test.cmd”. Approve the prompt that tells you changing the file type might cause your world to stop.
Now try and edit the test.cmd file – right-click it, select “Edit”.
Jesper and I both get the following message:
At the moment, I just can’t think of a good explanation – do you get the same behaviour?
We’ve already discovered that it doesn’t seem to happen if you had a fresh install of Windows Vista, only if you upgraded to Windows Vista from Windows XP.