James – I just saw your comment today. You can reproduce two of the problems as follows (both assume Firefox as the default browser):
1. Drag a URL from the address bar to the desktop to create a shortcut. Then close all Firefox windows and click the shortcut. The requested page in a Firefox window does appear, but the error message described in the MozillaZine article appears accompanied by some alert bell tone.
2. Close all Firefox windows and launch a URL from a PowerPoint presentation. Something goes wrong, I forget the details and forget whether it applies to web or local URLs. I’ll try to remember to characterize this next time there is a Firefox upgrade.

I see this on 4 of 4 computers tested, 3 Vista and one XP. It is annoying that I need to edit the registry to fix this known error every time Firefox does even the most minor update. All one does to fix this is delete registry keys written by the Firefox installer – this seems like a problem that should have been fixed long ago.

I run Firefox Portable (exclusively) and this is still at 2.0.0.6. Anyone got any insights into why this doesn’t get updated?

Mickey, I don’t have that problem. How does it manifest itself?

So many fixes and still no fix for the shortcut bug:
http://kb.mozillazine.org/Windows_error_opening_Internet_shortcut_or_local_HTML_file_-_Firefox
It is annoying to have to edit the registry on every computer every time Firefox does an update.