You may have a compressed version of notepad.exe stored in a Windows
installation folder {likely I386}. Do a search for notepad.ex_. If you
find it, you can use expand.exe {same folder} to expand the compressed file
to replace your current notepad.exe files.
My computer has notepad.exe in C:\Windows and C:\Windows\System32 folders.
The path from All Programs for Notepad is to the copy in the system32
folder. If you also have two copies you could try replacing the shortcut
path to Notepad with the other copy. You can find the path by right
clicking on Notepad in All Programs and selecting Properties.