Followed this tutorial How to install Iceweasel 4 on Debian? in attempt to install iceweasel 4 on my debian 6 "Squeeze" machine.
After installation it seems that I can only open the first instance of iceweasel from Applications/Internet, but not from commmand line.
Trying to open it from command line results in this error:
/usr/lib/iceweasel/firefox-bin: symbol lookup error: /usr/lib/libcairo.so.2: undefined symbol: FT_Library_SetLcdFilter
If iceweasel instance is already running I am able to open a new instance of iceweasel from command line without any errors.
Edit: I am using Gnome window manager in this setup