When viewing an XHR response in Safari, occasionally the response is stuffed into a tiny window/frame that cannot be resized. In Chrome, no XHR response is visible whatsoever. Windows XP.
<rdar://problem/7046375>
Does this happen on Mac, too? Having a reproducible test case would be very helpful.
This was a Windows-only problem. It seems this has been rectified with Safari 4.0.3 (531.9.1) as it is no longer reproducable.