Thanks for the replies. Are you using a FireWire drive by any chance? Many users have experienced these issues when using FireWire drives. If you are using FireWire, do you still get these problems when you disconnect it, boot up, and run LimeWire again?

Oh, and you basically become an Ultrapeer depending upon whether or not the part of the network you connect to "needs" an Ultrapeer at that time -- if you connect to another Ultrapeer that already has leaves and has open slots, it will tell you to become one of its leaves.