Lesly,
Have you tried clearing your browser's cache? It could be that your browser has cached a javascript file that for some reason was corrupted. Flushing the cache would force your browser to redownload all of the forums javascript files, and possibly clear this up.
If that doesn't work, post a link to one of the posts where this is happening, and I'll take a look to see if anything is fishy.
Thanks.

Mike