Hi,
I also move sites around a whole lot, on the same host, or to different ones. I don’t know if this is exactly analagous, but I have found similar problems when moving to a new host, specifically when using a funky URL that isn’t the fully turned on "real" domain.
Looking at your URL, I’m guessing that you might need a temp different setting for RewriteBase in .htaccess.
My guess would be that you currently have this in .htaccess:
RewriteBase /
And if so, I’m thinking that this might work (because of the subfolder):
RewriteBase /sledisland/
If that works, great, and when you turn on the "real" domain, be sure to restore the RewriteBase back to the first setting.
If none of that works, you could leave FURL’s off until the domain switch. When the switch takes place, I’m thinking that your original settings should work fine.
That’s my best guess without seeing the innards of your site. Don’t forget to double-check your settings in the manager for File Base Path and File Manager Path. If something needs to change there, your phpinfo file will contain the path.
Also, you can check in the root of the site, and make sure there isn’t a goofy bogus default.html (or the like) messing up the loading of index.php.
Good luck, Dave