Yes well.. i dont see the problem, one single card can do so much these days. Are you editing the blockchain by hand ? how is that even possible to lose blocks after a lot of confirmations (and new blocks)
I think i will have to implement some extra security feature on yiimp to handle that (to virtually double or triple the confirmations required)
It's possible if they are mining the same chain off-line. Then when the big miner goes off, they publish their longer chain. I didn't know this was still going on, and I defer to funkenstein_ to talk to the now rogue chain rewriter.