Microsoft has introduced a bug into most versions of Windows Internet Explorer whereby s/(\S)\s+([,.;:/]\S)/$1 $2/g
Now, web browsers usually stretch out a page horizontally to accomodate non-breaking spaces, and MSIE is no exception. So any user can stretch out a page on a site that allows comments posting by just inserting a "." (or , ; :
So what to do about it? I tried various things like converting spaces to other characters (like the new ‌, thanks TorgoX) but it didn't do the trick. The only thing that works is to either disallow such text, which is unreasonable -- we won't let Microsoft's bug dictate that people can't use PERIODS in their posts -- or we could match the pattern and insert an (yes, you're reading right, inserting a non-breaking space actually tells MSIE to break where it previously wasn't breaking! wooooo!), but that too is munging a user's comment text because of a Microsoft bug. It's less intrusive than disallowing overabundance of periods, but it is still annoying, and we don't want to do it.
And of course, we get a lot of people saying there's a "bug" in Slash. It is a bug in MSIE. There is no bug in Slash relating to this. To say otherwise means you are a liar, or you are ignorant.
So we are stuck with either munging user input or just letting Windows MSIE users deal with it, and optionally complain to Microsoft. For now, we've chosen the latter.