Have you tried using the developers tool kit to search for the string 'TEXT_REMEMBER_ME'? It should show you immediatly where that string is located.

In Admin, if you go to Tools --> Developer's Tool Kit and then scrool the the very bottom text field. Type in the string you are looking for (TEXT_REMEMBER_ME) and set the drop down to say All Files - Catalog. Click Search. You will then get a list of all of the locations and line numbers that this string appears in your catalog files in Zen Cart.