I would like to mention that I too have been getting these errors.

I am running from within the folder.

I had .net 3.5 installed (reinstalling to 3.0 to try that now)

I'm running windows XP

I do not have UO 'installed' but I do have it fully patched (it's not within the registry, just a copy of the game folder)

My OS is an English version so I don't believe that to be any issue.

This problem has followed me across 3 installs of this OS, I normally just give up and fire up a server emulator to play with or visit test center, but I thought I would come here and post and maybe help solve a bug if one does indeed exist.

edit: after posting this I discovered that part of the bootcamp procedures, it installs .net 3.0 already for me. Maybe this installation of .net, direct from the boot camp driver disk created by OSX is the culprit. Will uninstall that version and install the copy from Microsoft.