y en algunos momento es culpa de desinstalar el Dreamweaver CSx y por ende aquí enontré la causa y solución
Causa:
Se haya eliminado la subclave de Registro ShellNew, o bien la extensión .txt ha quedado mal asociada.
Solución:
crear manualmente el fichero y de paso ver su contenido, copia y pega el siguiente texto en Bloc de notas, pulsa Archivo, Guardar, escribe "Asociación_txt.reg" (con comillas) y pulsa sobre Guardar.
Windows Registry Editor Version 5.00 [HKEY_CLASSES_ROOT.txt] @="txtfile" "PerceivedType"="text" "Content Type"="text/plain" [HKEY_CLASSES_ROOT.txtPersistentHandler] @="{5e941d80-bf96-11cd-b579-08002b30bfeb}" [HKEY_CLASSES_ROOT.txtShellNew] "NullFile"="" [HKEY_CLASSES_ROOTtxtfile] @="Documento de texto" "FriendlyTypeName"=hex(2):40,00,25,00,53,00,79,00,73,00,74,00,65,00,6d,00,52, 00,6f,00,6f,00,74,00,25,00,5c,00,73,00,79,00,73,00,74,00,65,00,6d,00,33,00, 32,00,5c,00,6e,00,6f,00,74,00,65,00,70,00,61,00,64,00,2e,00,65,00,78,00,65, 00,2c,00,2d,00,34,00,36,00,39,00,00,00 "EditFlags"=dword:00010000 [HKEY_CLASSES_ROOTtxtfileDefaultIcon] @=hex(2):25,00,53,00,79,00,73,00,74,00,65,00,6d,00,52,00,6f,00,6f,00,74,00,25, 00,5c,00,73,00,79,00,73,00,74,00,65,00,6d,00,33,00,32,00,5c,00,73,00,68,00, 65,00,6c,00,6c,00,33,00,32,00,2e,00,64,00,6c,00,6c,00,2c,00,2d,00,31,00,35, 00,32,00,00,00 [HKEY_CLASSES_ROOTtxtfileshell] [HKEY_CLASSES_ROOTtxtfileshellopen] [HKEY_CLASSES_ROOTtxtfileshellopencommand] @=hex(2):25,00,53,00,79,00,73,00,74,00,65,00,6d,00,52,00,6f,00,6f,00,74,00,25, 00,5c,00,73,00,79,00,73,00,74,00,65,00,6d,00,33,00,32,00,5c,00,4e,00,4f,00, 54,00,45,00,50,00,41,00,44,00,2e,00,45,00,58,00,45,00,20,00,25,00,31,00,00, 00 [HKEY_CLASSES_ROOTtxtfileshellprint] [HKEY_CLASSES_ROOTtxtfileshellprintcommand] @=hex(2):25,00,53,00,79,00,73,00,74,00,65,00,6d,00,52,00,6f,00,6f,00,74,00,25, 00,5c,00,73,00,79,00,73,00,74,00,65,00,6d,00,33,00,32,00,5c,00,4e,00,4f,00, 54,00,45,00,50,00,41,00,44,00,2e,00,45,00,58,00,45,00,20,00,2f,00,70,00,20, 00,25,00,31,00,00,00 [HKEY_CLASSES_ROOTtxtfileshellprintto] [HKEY_CLASSES_ROOTtxtfileshellprinttocommand] @=hex(2):25,00,53,00,79,00,73,00,74,00,65,00,6d,00,52,00,6f,00,6f,00,74,00,25, 00,5c,00,73,00,79,00,73,00,74,00,65,00,6d,00,33,00,32,00,5c,00,6e,00,6f,00, 74,00,65,00,70,00,61,00,64,00,2e,00,65,00,78,00,65,00,20,00,2f,00,70,00,74, 00,20,00,22,00,25,00,31,00,22,00,20,00,22,00,25,00,32,00,22,00,20,00,22,00, 25,00,33,00,22,00,20,00,22,00,25,00,34,00,22,00,00,00