Truble with Gosu

Hi everybody!
As a relatively new Linux user, I’m having troubles running Gosu
library (http://www.raschke.de/julian/gosu/) in Linux (Ubuntu 6.06
Dapper).
After a painful -for a newbie- process of installing dependencies, I
made Gosu’s instalation the first time successfully, even opened the
tutorial examples. Next time I started my computer, it didn’t work.
Here is the error message. Curiously, is different with the different
versions of Ruby. (Used 1.9 first time that ran)

Tutorial.rb::30 in ‘initialize’ : Error initializing output devie.
(RuntimeError)
from Tutorial.rb:30:in ‘initialize’
from Tutorial.rb:90:in ‘initialize’
from Tutorial.rb:128

and with 1.8, I get the following:

Tutorial.rb:83 [BUG] unknown type 0x12
ruby1.8.4 (2005-12-24) [i486-linux]

Any clue what would be wrong?
And BTW, I couldn’t find any Gosu bug documentation anywhere, it would
be useful to keep track of the bugs.

Thank you. Ruben.