Help: ModelSim doesn't respond to keystroke

I just installed Quartus 7.2 on Fedora Core 8 Linux, including the ModelSim AE 6.1g came with it. When I tried to use the ModelSim, everything seems fine except that the GUI does not take any keystroke. When I type, nothing happens. I can run the simulation in batch mode in the Linux shell, simulation compiles, runs, and generates waveforms just fine. And I can load the waveform into ModelSim GUI and debug it, as long as I use mouse only. Everything works just fine except typing in the GUI.

Anybody had this problem before? Any idea?

Thanks!