Probably because you are using IE and in some fit of insanity, IE doesn't wrap on whitespace that is followed by a slash.

To test your browser, view this node directly to see a line full of whitespace that won't warp at all under IE:

I actually started to edit the offending node but then was at a loss for what to do to fix it. I hate breaking things to accomodate bugs, but I guess IE is way too popular to just ignore this particular case...

Update: I put in some CODE tags which should fix the problem for most people. If you have "auto" code wrapping and a wrap length too long, then the (sane) wrapping code will think that nothing needs to be done (because of the frequent whitespace) so the (insane) browser (IE) will still make things way too wide.

Update: Just for completeness, I'd like to mention that IE also gets it wrong by wrapping after plain hyphens.