All you have ot do is take out two links (1 inch) at a time until you get a length that causes the lower pulley to swing down slightly and not hang loose of rub on the RD cage, when the ends are brought together (in the little ring and smallest cog).

This is the second time for this question this week. Looks like a daily problem.

http://www.bikeforums.net/showthread.php?t=601646