There may be a workaround -- when you get the database error, the error message itself has the URL for the direct download of the file you're trying to reach. For example, when I click on my AU Spell Spreadsheet, part of the error message says:
'http://www.enworld.org/modules/Downloads/store_folder/Electronic_Aids/auspells14.zip'
If I remove the quote marks at the beginning and end, copy and paste that into my web browser, the file starts downloading. Likewise, the Castle Guide conversion link appears to be:
http://simonwoodside.com/dnd/download/ -- and I tested it and it indeed goes to the right place.