Yeah, when I see people running Ubuntu for their production servers I always assume it's developers with minimal system admin experience who just want to use the same distro for their server as their desktop. I've got nothing against Ubuntu, and have even used it to convert a few windows users over, but if you're going to run a production server then install Debian on it.
I have been using Debian since 1996, and became a package maintainer in 1997, a position I held for nearly a decade until I began to not have enough time for it. While continuing to think that Debian is a first-rate effort, I got tired of certain aspects of it, and moved to Ubuntu, lock stock and barrel. I actually like to have my desktop system marching in sync with my server, so that the packages are pretty much exactly the same. And you know what? Ubuntu works pretty well on the server, and comes out with nice regular releases, allowing me to decide, and gauge, time-wise, when to upgrade. Certainly, like everything else, it has its defects, but by and large, I've had good luck with it, as both a desktop and server distribution.
Well it was our operations guys who refused anything but Ubuntu because "they had installed it at home". We now no longer have operations guys and the development team own the infrastructure :)
Do you have links to bugreports to your problems by any chance? Or more detail on what problems you ran into so I could have the Ubuntu kernel team check them out?