Which version are you using exactly 18.104.22.168-fuse or 22.214.171.124 fuse? I tried with later and is working fine on Ubuntu 8.10 box here.
One more thing what does your LANG variable set to? I am using en_IE.UTF-8.
From the InstallAnywhere knowledge base:
Solution was to unset one or both of TITLEBAR and PS1 env variables prior to running the installer.
Thanks for your quick answers.
My lang is en_US.UTF-8 and using 126.96.36.199
Since you pointed out a PS1 or TITLEBAR problem, I decided to run the installation from the "Alt+F2" as I'm using the desktop, and it just worked.