I've had that (save loads to very end of bar and then crashes). For me it was due to bad cc being installed or something happened to the saved game itself.
I go through my mods and cc to make sure they're good. When I can't figure out what the issue is with the save I just start a new save. lol
It's odd that a fresh copy of Builder's Island isn't loading. That tells me it may have become not recognized by the game.
We've got a post
here that might help with that. - Get Store Content Recognized By Game.
Builder's Island isn't store content, but it is a .Sims3Pack file, so I feel the linked info still relates.
I'm curious if you find out what happened.