I have a similar problem, hopefully its related.
No.
I'm running Ubuntu 11.10 and when I try start the utility from the command line, I get a whole lot of gtk critical errors (mostly to do with widgets), and the whole computer hangs. The only way out is a hard restart since the keyboard and mouse become unresponsive.
That's really strange, and I suspect a problem with Ubuntu here: first, a user program shouldn't be able to crash the OS. Second, Rockbox Utility uses Qt and not GTK, so you shouldn't get any messages regarding GTK. There's a Qt style that uses GTK but the prebuilt version of Rockbox Utility is statically linked against Qt.
Am I perhaps missing some libraries for the utility to work?
I can't think of any -- Rockbox Utility is statically linked and if there are libraries missing it wouldn't start instead of crashing your system.
You could try compiling yourself, it's not really complicated on Linux.