Wow!!! Now that you have found the flaw... Can you please help us with an idea on a fix? This coin is more original than the other 99% out there, imho !!!
As far as I know, there is no proven way to make a block reward not predictable and not miner selectable at the same time.
It
might be possible to use the discovered blockhash to choose reward, but that would likely require some significant changes to the underlying protocol.
Please consider communicating this (your findings and your tests) directly to s4w3d0ff and myself so that we have a chance to possibly fix it before you release it into the wild. We're both in the IRC (#cganomaly @ freenode), though he is currently AFK. You can also message us via bitcointalk if you prefer. If we are able to release a fix before the general public has access to it, there may be a reward for you.