Posted July 12, 2011
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Start with an installation of the basic game, as received from Steam, with nothing else.
Verify that the installed version of the game is 1.2.0.416. If it is any other version stop there. Problems with files being overwritten or conflicting are usually a sign that you have the wrong version.
Install OBSE and OBMM, before installing anything else. The order of these does not matter. Installing OBSE on Steam requires special instructions, which I linked to in an earlier post. Install OBMM before installing any "Unofficial Patch" or anything other than OBSE.
Note that when OBSE is installed, Oblivion must no longer be launched from its own loader; you must launch obse_loader.exe to start the game. Make sure the game starts correctly from obse_loader.
After OBMM is installed, use the OMOD versions of the Unofficial Patches. Do not use the executable or zipfile versions. Let OBMM install and activate the OMODs for you.
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http://www.tesnexus.com/downloads/file.php?id=5296
there are 5 different packagings of the Unofficial Oblivion Patch. One of them (read the titles) is the OMOD packaging.