Oldkayaker, this is happening because the site does not recognize information saved from your browser; when entering the data on, say, "Location", if the data is autocompleted from your browser, the location will appear in the field correctly, but you will still get the "red border" and "Invalid parameter" error.
To correct this, all you need to do is enter the data manually again, until the site's own data appears. You do not want to use "autocomplete" from your browser. This is a bug that has to be addressed by the programmers.
Cheers
Vlad