Just export any iWork KeyNote to HTML and try to open it with WebKit. It gets hung just in the first page before rendering it showing you an unending spinning icon. Besides, you can open it perfectly with FireFox.
It seems that you're using something different than Safari 5.1.5. Please report bugs about unreleased versions of Safari via <http://bugreport.apple.com>.
(In reply to comment #1) > It seems that you're using something different than Safari 5.1.5. Please report bugs about unreleased versions of Safari via <http://bugreport.apple.com>. I've used the last nightly built and I've updated to the last Safari 5.1.5. Did you test the problem?
No, I haven't tested with Safari 5.1.5 and nightlies before. Indeed, this is reproducible in this configuration.
<rdar://problem/11024330>
Even though this is reproducible with Safari 5.1.x, it's nonetheless a result of running unreleased software on this system previously. It's unfortunate that that had such an effect even after uninstalling. This is not a WebKit bug, so closing as INVALID per our policy. We'll keep tracking this internally at Apple.