Yeah.. I guess it can't solve the genesisblock of e.g. PeerCoin. There are some different "magic numbers" in the block, at least the CBigNum(4) -> CBigNum(9999)

https://github.com/bitcoin/bitcoin/blob/0.8/src/main.cpp#L2779
https://github.com/ppcoin/ppcoin/blob/master/src/main.cpp#L2272