Fx 1.5 20051111 Stable: Pages Not Rendering *At All*

When I attempt to go to several webpages, the page never loads *at all*. 
  This problem manifests itself in various ways, depending on what's 
going on.

1) Normal link clicking
The progress bar increases and the rotating 'loading' indicator is 
active, but eventually the status will say 'done' although the page 
didn't change.

2) New Tab or New Window
Almost immediately the status will simply say 'done', only rendering a 
blank page.

I've tried googling for the answers to all this, didn't find a thing 
related to the queston.

For reference, my box is XPSP2, running Firefox build 2005111111 Stable.

Null Shadow