Am using windows 7 64bit.
Completely Reinstalled Rome 2, deleted all files in the appdata folder, followed instruction on how to install gem, reinstalled the . Then I saw someone having trouble with razer cortex, but not in my case. The sinner is the synapse 2.0 crap that have caused so much havoc on so many software. I can use my old mamba driver, but for newer mouse you need this software so you are forced to use it. Weird thing is the standalone installer work on attilla no problem. Only rome 2.

Hope that it fixes your problem