i had the same problem like 1 min ago... you need run newest gproxy 1.73 then open euroloader then change realm to eurobattle GPROXY not normal one and if error will apear about WC3 path download wc3 fixer from this forum
then run it again and it should work
i just copied same post 2nd time now because 2nd guy didnt know how to fix it...
maybe you (admins) should make a topic where is everything clear i mean with changing realm to gproxy etc.