Internet Explorer 8 Hangs - Firefox won't terminate process

I am running WIndows 7 - 64-bit.  I thought my problem was solved, but it turns out that my Internet Explorer version 8 still hangs every time I (or a program/link) tries to open it.  I can directly open the Internet Explorer 64-bit version on my system, but most of the links and programs that try to open the browser default to the 32-bit version (both are on my system).  

When I try to use Firefox the browser opens fine, except that after I close it - and then try to open it again - I get a message that the program is still running.  Then I have to go into my Task Manager to terminate the Firefox process before it will open again.  This seems to be a separate and unrelated problem to the Internet Explorer issue, but since they are both browsers and the problem occurred at the same time I thought I should mention it.

I think that if I make the 64-bit version of Internet Explorer the default browser on my system the problem might be solved.  I already tried the previously recommended solutions regarding eliminating potential conflicting start-up programs, although I can't get into IE 32-bit to make sure that the add-ons are all disabled.  How can I get into the program to disable the add-ons, or (as an alternative solution) how can I make the 64-bit IE or Firefox my default browsers?

Thanks,

Phil