I've recently encountered this problem on a new office server. Your post prompted me to have a proper look at this to get this issue resolved. The server provider set up a moodle installation for me and this is where the problem was, the "$CFG->wwwroot" address in config.php was incorrect:
Changed it and now works great from every location from which I access it i.e. topic sections appear as they should.
Hope this helps.
Thanks Ray - I was on the trail I knew it was the path but I wasn't to keen on changing the config.php file.
I was looking at my settings and I change the slash arguments and it was fine. I wish I had thought of it sooner. This also fixed the HTML editor problem.
Hope this post helps someone!