Is the pool under attack? Reject-rates are through the roof for some selected miners (one of them is mine). 10GHs rejected seems like someone is trying to DoS the pool?
It's probably just h2o's upgrades... As he said here:
For the next hour or 2, your hashrate will be shown as lower than it really is. It shouldn't affect your payout though. I'm doing some upgrades that had unintended side-effects for the stats page.
I'm sure this thread will be filled soon with complains!!
This increase in hashing power most be draining your time and the servers. This must be becoming a full time job for you.
I wouldn't cry wolf/hack/DDOS just yet.