To permanently enable user ID and password Auto Complete on all websites and web pages regardless of website setting, go to C:\Program Files\Mozilla Firefox\components folder, and edit the nsLoginManager.js file.

Locate the following lines of code (around line 725 to 727 in Firefox 3), and the comment out the lines by adding // (double slash) in front of the lines.

Before:

Code:
if (element && element.hasAttribute("autocomplete") &&
element.getAttribute("autocomplete").toLowerCase() == "off")
return true;
After:

Code:
// if (element && element.hasAttribute(”autocomplete”) &&
// element.getAttribute(”autocomplete”).toLowerCase() == “off”)
// return true;
After editing, save the file and restart Firefox browser, and now all passwords can be saved.