Using the 6.0.1293 version, I am meaning both the Sandbox and SafeZone feature. Problems are intermittent, not so frequent. Still, they are there.
-Sandbox: Sometimes with FF 5.01 all the plugins and toolbars are not loaded. Actually, at least the adobe plugins (all of them), the java one, and the AVG link scanner toolbar are concerned.
-SafeZone: It happened once. Upon opening it, the Google chrome browser would not open and instead the whole computer would freeze there. Only way out would be to force shut down and restart normally Windows.