The most common cause would be that the patch installed in the wrong place, instead of overwriting the Rome Gold files as it should have. I assume we're talking about 2.32c, right?
I'd recommend a full clean reinstall outside the system path. Uninstall the game, and then manually delete the game directory - this is important. Reinstall Rome:Gold - choose a new directory like c:\games\rome instead of the suggested path. Download the 2.32c patch, and run it to install it; make 100% sure you point it to that same new directory above so that for instance the new rome.exe overwites the old one, the new romegame.exe overwrites the old one, and so on. Once done right-click on the game's desktop icon and set it to run as administrator, and to disable desktop composition.