Thats weird, when I first installed CoD (like many with AVG) the rendobj.dll file came up as a virus and AVG deleted it. Updated AVG and no more problems but now I have used the search option for that file and it doesn't exist. ....
Not sure where that file is supposed to be located or even if it is used anymore after the official patch (I seem to recall it was mentioned in the update notes as the 'AVG false positive issue being fixed'). Best take a look at the official patch notes in your CoD folder regards that file.
Post your system specs, OS, DX version, screen res, etc, I would use the Steam 'verify cache' to get CoD back to the official patch and get it launching with that - then apply the later Beta patches.