When writing a post by using Internet Explorer 10, it is often not possible to create line breaks by pressing enter.
I believe this is a problem in many vBulletin forums, IPB forums, and many web forms.
Easy to say, "Don't use IE10.", but maybe vBulletin has this fixed in the latest version? does not seem to want to fix it. I think they say it is a problem with the forum software.
Does not affect Chrome or IE8 or IE9 though.