I'm glad Sal has posted this, as I've had a similar problem for some time, but been too busy to ask for help.
Instead, I took the temporary way out (return to Internet Explorer ) & am finding it a real pain after getting used to Firefox through 2 previous versions - though far from expert.
Unlike Sal, I don't know what I changed at the time. Nothing drastic - well, not on purpose, anyway.
I have uninstalled older versions & installed 1.0 twice.
(I recall that one of those didn't at first disappear in Add/Remove, so I think I deleted files separately. A clue perhaps..?)
It should function in theory, but nothing comes up on screen except the hourglass, which joins the cursor. That hourglass then stays when I access other webpages, but doesn't stop me doing anything except view Firefox)
As Firefox 1.0 is on the new February PC World CD, I wonder if installing from that would make any difference?
Grateful for any advice.