i posted this on the logicprohelp forum, but hopefully someone will find this useful here as well.
i had this problem last weekend on my early 2008 mac pro running 10.5.2, and it was driving me nuts.
in fact, it was pissing me off so much that i bought a copy of battery 3 to use instead of ultrabeat. it's unbelievable that such a glaring bug would crop up, so i'm hoping this bug is more of an problem with the changes in leopard than logic.
i finally got ultrabeat to correctly load up samples by first running the OnyX utility to fix permissions on my startup drive. not sure if that was necessary, but i wasn't leaving anything to chance. and then when i was building up my own kits using David's Sample Playback Sampler (see
Logic Pro Help :: Log in), i intentionally skipped (i.e., left empty) the c1 key where the kick drum is usually placed and shifted my kit a semitone up. i saved the ultrabeat setting and now everything loads up correctly. the c1 key is still messed up and loads some random taiko kick drum (lol) each time i open the project, but at least i'm not pulling out my hair anymore trying to have logic load up the samples in my saved kit.
hope this works for someone else too, but for now this seems to be my work around until it gets addressed by apple.