*(Note: this article applies to eLicense only, and does NOT apply to our new Online Activation System)*
The Runservice.exe file is created automatically when you install and first launch a game that is using eLicense. The fact that it's missing indicates that your Windows is having trouble with it: it could have removed the file, or, as the error indicates, flagged it as unexectuable for some reason.
This could be because you have installed the game into the wrong directory (64 bit instead of 32 bit), or it could be an indication that Windows Vista/7/8+ UAC (*user account control*) has blocked the proper installation of your game.. Make sure it's installed correctly. You will also most likely need to set the game's properties to "Run as administrator". If that doesn't do it, then also try and adjust the compatibility settings and see if one of them works.
Sometimes manually copying that file into your Windows system folder works. Submit a ticket if you're stuck and we'll send you the file. However, this is an attempt at a workaround of an underlying Windows issue, which sometimes works, but often doesn't. You may run into other problems if the correct game installation was blocked by your UAC settings, even if the game appears to work after manually copying the runservice file. It may be a good idea to completely uninstall the game, reinstall from scratch and make sure that you right-click and select "Run as administrator" during installation and the very first launch of the game.
Disabling UAC during the installation may help, too. You should also perform theses steps if the game still doesn't launch despite copying the file.
'Runservice.exe' actually runs as a Windows Service for our eLicense system. There will be registry entries for this to launch in that fashion that don't get inserted into the registry by just copying the file to the '\Windows' directory alone.