GPS hangs while scanning host for available compilers

Hello,

I was running GPS this morning and wanted to add an executable to a project.

I have clicked on "Project > Edit project properties". The the windows 
"scanning host for available compiler opens" but it never returns... I 
can close it with "Alt + F4" or by clicking the cross icon but I can't 
edit properties.

I think it is the first time I run GPS since I upgraded this machine to 
Ubuntu 12.04 (but this doesn't appear on other machines under 12.04).

Any idea?
Mathieu