False Steam Virus Alert

I cant use Steam because Avast gives false Trojan Horse virus alert.
Win32:fakeAlert-AAB [Trj]

Little help please?

PROBLEM SOLVED! Just needed to update program.

Well.After Eset i used Avast Professional 4.8 and it was detecting Steam.exe as a virus but now i have Avast Internet Security 6 and problem solved!!!