About Firefox:
Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.0.10) Gecko/2009051602 Gentoo Firefox/3.0.10
A bunch of garbage buttons appear when running FF 3.0.10; see screen capture. When I set "User Agent Switcher" to Opera 8.5.1 the same thing happens. When I set "User Agent Switcher" to IE6, the problem goes away and Slashdot looks normal. This is all on FF 3.0.10, simply claiming to be FF or Opera or IE. It's definitely a bug in the CSS that you're sending out to non-IE users. The Slash version is whatever Slashdot is running as of June 7, 2009
Screenshot of garbage buttons
I'm seeing the same thing in FF 3.0.9 on Debian, with the user-agent Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.0.10) Gecko/2009042805 Firefox/2.0.0.5 (Debian-3.0.9-1)
I am seeing the same behavior on FF 3.0.10 on OS X 10.5.7. My display shows colorful pill type buttons along with the grey bars. I am unable to highlight or interact with them using the mouse.
It only appears for me when the comments get three 'replies' deep. It does not do this when I am logged out of the site.
Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.5; en-US; rv:1.9.0.10) Gecko/2009042315 Firefox/3.0.10
Safari (5530.17) exhibits the exact same behavior.