That's a small problem that can however cause some headache:
The installer crashes after downloading the installer code and trying to resume the installation.
The message shows something like "installer stopped unexpectedly with return code 1"
The reason and the solutions are rather silly:
When Firefox / Icewasel downloads the installer code it puts it into /root/Download/Firefox, from where it's not accessible.
The solution is as simple as telling Firefox do download to the desktop; the installer will find it automatically and the installation will work like a charm.
Note: This problem/hack may seem and is indeed trivial in the case of normal installs, but it may be a mayor PIA when you are doing an install from an USB stick into a netbook (Acer Aspire One in my case).