GLException: Error making context current on Ubuntu 64

I’m testing a JOGL application. It works on Windows and Mac and most Linux platforms. One of our testers has 64 bit Ubuntu 8.04. Whenever he tries to draw anything using JOGL he gets a GLException thrown. He has an ATI card; we’ve tried changing drivers between 8.543 and 8.582, but neither makes a difference.

The GLException is thrown from com.sun.opengl.impl.x11.X11GLContext.makeCurrentImpl(X11GLContext.java:141)
, which simply tells me that the native method to make a context current failed.

Any help on what might be going wrong, or anything to try, would be appreciated.