Big Problems after Upgrade

Hi,
I am running Mozilla 1.7.8, or rather, attempting to, after upgrading from
1.7.6, on a Win2k machine.  When the browser opens, the title bar says "Sign
In - Mozilla" and the menu bar is missing several items.  All I get in the
menu bar is "View, Go, Bookmarks".  The program is frozen: It won't allow me
to enter a URL or select any other item on the page.  Ctrl-2 will not take
me to the mail.

I uninstalled and reinstalled several times with no luck.  I also
uninstalled and went back to 1.7.6, and it now exhibits the same symptoms.
Since the only thing left was the profile I restored all that information
with MozBackup.  Still no luck.

Does anyone have any ideas of what I should try next?  Having to write this
with MSIE really sucks.  Help! I'm desperate.

TIA
Bob