Because the codebase for my app includes full stops, (eg. .co.uk), my web start cache is in a folder with full stops in its name. When I try passing the path for my .hs file to the HelpSet constructor, it dies horribly. This doesn't happen if I don't use the fully qualified URL for my codebase, but then the app can only work if the client machine knows what server I'm referring to. This kind of defeats the object of Web Start so I'd quite like to fix it! I've tried using java.net.URLEncoder.encode but of course that leaves full stops alone, no use to me at all. Can anyone help me out? I assume there must be some way around this, probably a very obvious one.