classic situation? really.. dont think so.. last generation was 14 hours ago.. network hash is down... there is no "strong" mining on this coin...
UFO is a small coin and there is not a massive amount of mining power, we will change that but these things take time, updating to the latest Bitcoin and commissioning additional services are what we can do to get UFO noticed.
About the stalling blockchain, what's classic is the miners leaving when the difficulty is high, what's not classic is the unusual and broken difficulty adjust in UFO which allows the difficulty to jump too quickly too soon, miners leave and the chain gets stuck. There's another situation where you end up with low difficulty and the chain gets stuck, I'll explain with some background, there are numerous 51% attacks on smaller coins, even devastating for some like HTMLCOIN which is launching a new coin to compensate exchanges as the loss has been so great (I've built the replacement coin for them which is based on Qtum), to prevent this we employ automatic checkpointing to prevent the chain being rolled back, with low difficulty you can end up with lots of long competing chains and sometimes it is not the longest one that gets checkpointed, those clients latched on to the longer uncheckpointed chain have to wait for the shorter chain to become the longer chain.
Both these issues are understood and will be solved with the hard fork in 0.10 to change the difficulty adjust. We would have had 0.10 out a month ago as planned but the NeoScrypt miner had to be updated which it now has been, we only need to now wait on new binaries. We can expect 0.10 out next week and the fork four weeks later, we need to wait that long to ensure that the majority of people have updated so as few people as possible are left on the old chain.
i use: UFO Client 0.9.0.
Do i miss some options in the conf file?
Pools can be a lot of hard work to get running. My only experience with pools is MPOS + stratum-mining. What pool software are you using and are you using a NeoScrypt module for hashing?