Ok, now I have the solution. Hope you are still reading... or maybe someone else who is interested. Anyway:

1) close the browser
2) open /home/user/.mozilla/microb/prefs.js with vi or an other editor
3) add following lines to that file:
user_pref("capability.principal.codebase.p0.grante d", "UniversalXPConnect UniversalBrowserRead");
user_pref("capability.principal.codebase.p0.id", "file://");
4) save

See here for details: http://groups.google.com/group/Tiddl...e8868f62086fe3
And here is a vi manual, if you're not familiar: http://www.cs.fsu.edu/general/vimanual.html