I am trying to learn the creation kit. I keep getting an error message on starting up to load the data files. The message is

Masterfile: Localization: Lookup failed for IDs from strings file: Strings/Skyrim-English.DLStrings

I do have such a file, and the beginning of the file looks like gibberish to me when looking at it with a text editor. Further down, there are actual snippets of text.

Have my files been messed up, or is there some other reason for this error message?