Do your sites link to each other? Are they on the same IP address, or in the same C class (IP addresses are identical for the first three octets AAA.BBB.CCC.****)? Chances are, you've been caught by the new "network of sites" filter.
DVD is right, you're penalised. Solutions:
1)Chage I.P's(dissimmilare first 3 octets') 2)Remove interlinking from the sites. 3)If the content duplication is there remove it. 4)Remove all the link that you think could be considered as bad neighbourhood.