Using Linux build M18 2000080308. Load up http://www.slashdot.org Notice the vertical black line between the second and third images at the top right. This does not appear under NS4. Sorry, don't know what component this is, so I'm filing it under browser-general.
*** This bug has been marked as a duplicate of 27529 ***
this bug doesn't need to be reopened, because bug 51286 has been filed.