I have reproduced the problem now. If you mine with a high difficulty, you sometimes get errors. diff >= 512
on yiimp and zpool you can set a fixed diff in the password like this:
-p d=256
diff 1-256 is working fine.
OK first 2minutes does not have this problem and after set diff to 256 don't get error anymore on suprnova.cc
Thank you for your great works !
Cheers.