yes looks like you have problems with some of your miners.
I have the same miner and had problems too - different kind though: https://bitcointalk.org/index.php?topic=438714.0
as far as I can tell I have a huge amount of stales which I can't seem to fix. Overclocking seems to make the number of stales increase. Overall ~ 13% of stales when running at 1300. Kind of sucks

good luck fixing your problem - I wish I went with S1's. bahh