I'm not sure anyone here can help me with this, since it's a problem with bibutils, but on the off chance that there is (and since bibutils doesn't seem to have any kind of support system), I'll go ahead:
I uploaded bibutils to a directory on my server, and the permissions are set correctly (750 for the directory, 755 for the files), and the path to bibutils in the database seems to be right, but I keep getting validation errors when I try to import an Endnote XML file. Upon further investigation, this turns out to be a problem with bibutils itself. Whenever I run it straight from the command line, I get a floating point exception, and it refuses to work.
Problem solved. Never mind. I just needed to recompile on my machine.