Wikimedia Bugzilla is closed!

Using alpha version as of 11JUN13. Did a small edit on Wikipedia English article "Nagato-class battleship" (deleting 3 letters from [Japanese] to form [Japan] in second sentence under section 5.1 World War II. Then scrolled down; after originally displayed area scrolled off screen, the screen went black in the TAB.  Other TABs in IE remained operative.  Back arrow did not produce any results on black screen or URL showing for the Wikipedia TAB.  Reloaded http://en.wikipedia.org in TAB with black screen; successfull load and correct operation thereafter.  Could not reproduce the error.