So I just installed 32-bit Squeeze. I've done exactly two things since booting into the first install: apt-get install gtk+2.0, and ./firefox, so unless gtk did something, this might be an easily fixable problem with Debian itself. After installing gtk and trying to run firefox via command line, it tells me
Error: cannot open display: :0
I googled a bit and couldn't come up with a solid solution, but the problem seems to be around other places. Any idea how to fix this?