Drop-down menu becomes unselectable in Safari

As of Lion (10.7), I have noticed from time-to-time, drop-down menus in Safari become stuck or uselectable. This is usually on dynamically generated pages where the values of the pull-down menu isn't part of a static HTML code (like a list of states). The page works fine after reloading. Haven't had this issue in other browsers and I have seen this happen in different websites, so it's not the site content/code either. Is this a bug in Safari? I couldn't find any related articles on the web, but I know it's not my computer becuase I've experienced the issue on at least 2 different Macs.