I recently installed Cobl with it's addons, UL: Ancient Yews, and Millstone Farm Cobl version. But after doing so, my game won't even load to the Bathesda logo before it crashes. I'm running oblivion through OBSE. I have the current patches for the game, no unofficial patches. Is there a way to fix this or should I do a complete uninstall and reinstall EVERYTHING?

You should post in the mods thread if adding mods is the cause of your problem. http://sites.google.com/site/oblivionpoinfo/troubleshooting/postlo. You should install the http://sites.google.com/site/oblivionpoinfo/stabilization/unofficial-official-patches applicable to your setup. The problem is probably an installation error. There is not reason to reinstall the game.

Yes post your mod load order list. I had problems too with a cobl house after I installed it - my problem was that I hadn't installed Cobl properly with all its components. I'm not saying that's your problem but folks can take a look at your list and see what's going on.