I think it's an issue with the pool rather than with your miner.  I was mining here without a problem until there was a sudden "bug" that jumped my rejects from <5% to >60%.  Our op said that this was an unintentional bug that would be fixed within a couple of hours.  I tried for a bit for a couple days afterward and the rejects continued.  I switched my miners over to a different pool and all settings worked normally with minimal rejects.

I keep checking back here to see if the reject complaints die down because I really like this site and pool.  But I think it's going to take an "aha" moment from the hosts before I can jump back in.