It is the xlive.dll file that is detected for whatever reason (well, for practically being a crack). It is a false positive. I got around it by downloading the beta update some time ago. But it stopped working and i had to turn off bitdefender temporarily to update the game.
Hi, try opening your game folder - for example C:\Program Files\Steam\Steamapps\Common\Age of Empires Online\
There open the folder prerequisites and try to install both vcredist.exe files. Also try installing the one in VCR folder.