Just to comment that everything seems to be working just fine by now
After trying a while...i figured out that my system was detecting a joystick named "Logitech Driving Force" in Control Panel->USB Serial Adapaters" (or whatever the translation is...sorry, i have win10 in spanish)...so i disabled it and reinstalled LGS510_x64.
Then i lunched GIMX and voilá!
Yesterday, i tried to use Win7 32bits and the whole setup run without any issues...
Hopefully, everything is running ok on my Win10 64bits system...so i can return win7 laptop to my wife
Thanks again!