Look through the exceptions list. Anything with tdr.com or turbodieselregister.com in it (check in the
www.* section, too), if set to 'Block' will mess you up. Also, make sure you're not set to deny all cookies.
If you still can't get it, you could clear all the exceptions and cookies, make sure you've set it to either accept all or prompt you for cookies, then come back and log in.
There might be an option in your TDR control panel, too, that if not set won't remember you...
The tabbed browsing is what I love about Mozilla. Want to open a new link? Middle click, and it makes a new tab at the top instead of opening the new page in the first window, or making a new window. I'll get 20-30 pages lined up this way sometimes, and it's a lot less clutter and a lot less time waiting for the pages to load, as they load in the background while I'm reading the first one.
--Ty