Firefox 1.5 won't load local files

I recently upgraded to FF 1.5.

The problem is I can't get it to read an html file passed to it from 
another application.

For instance, FF is identified as my primary browser in Dreamweaver. 
When I want to view the page I've been working on I hit f12 and it's 
s'posed to load in FF. Doesn't happen. Instead, FF opens a new window 
with the default webpage instead of the file I was expecting.

In another case, an applications' help files are HTML. Hitting the 
"Help" key results in FF loading a new window with the default/home page 
instead of the help file I was expecting.

If I d/l a an HTML file and I hit the OPEN option in the download 
manager, FF loads the home page again.

I created a 'user.js' file with the following:

user_pref("capability.policy.policynames", "localfilelinks");
user_pref("capability.policy.localfilelinks.checkloaduri.enabled", 
"allAccess");
user_pref("capability.policy.default.Window.open", "allAccess");


So, how can I get FF to load the desired html file as requested?

Thanx

Dale