I dug up the FireFox bug reports on this, and related problems:
It’s related to the javascript generated by VB to scroll the page - the named anchor is overridden. You can illustrate this by turning off javascript - the intended article will then position at the top of the page. If you read the bug reports, you discover that FF3 FIXED a bug, they didn’t create one. This version of VB generates browser specific code with a “scrollIntoView” argument which used to be ignored. FF3 is now doing what VB is telling it to.