I got the unofficial patches from Nexusmods, these are the Unofficial Oblivion Patch, Shivering Isles Patch, and the DLC patches. Programs I have used so far are Oblivion Mod Manager and BOSS. Everytime I play with the unofficial patches
activated, the game won't launch. When I play without them, no problems. Not sure what I'm doing wrong. I patched up and played Fallout 3, Fallout New Vegas, and Skyrim on my PC. I didn't think I'd have a problem with Oblivion.

OK, according to the data files mode on the game's launcher, it mentions that there are three invalid files. They are Unofficial Oblivion Patch.esp, UOP Vampire Aging & Face Fix.esp, and Oblivion Citadel Door Fix.esp