I'm not sure if this has been reported or not, but saw other issues about layout in this thread, so thought I'd add my 2 bits. As you can see in the attached image, the layout for the user information that is on the left isn't always large enough so the next post in the thread is caused to be over to the right relative to the previous post.
I'm guessing from looking at this that the block that holds the user information needs to have a minimum size that is set by the amount of information present (name, role, forum rank, avatar, etc...).
This is with Firefox 8 on WinXP.