I'm also having problems commenting, and it's not happening on LJ, only here. Windows XP Professional, Firefox 3.6.16. When I'm typing in the comment box I can't click into the subject line OR click back to another part of the comment. So if I make a typo, I have to erase back to there using the backspace key to fix it, can't just click there with mouse or use arrow keys. Also when I select a block of text the selection won't hold long enough for me to copy or anything.

Edit: Having now gone to edit this comment, the arrow keys and mouse are working fine. But they stop working when I go to post a new comment again.