I always thought that this was a reliable way to determine which program is used to open a file with a certain extension when you double click it in Windows Explorer.
C:\>assoc .txt .txt=txtfile C:\>ftype txtfile txtfile=%SystemRoot%\system32\NOTEPAD.EXE %1
The above is my actual result. But it is UltraEdit that opens my text files.
Is this method not so reliable after all? Where can I see (and change), with a command or in the registry, which program opens my text files?