Only if there happens to be a web server on the wrong address, and it doesn’t serve the page requested (which would be odd if OP is just trying blah.com/). If the wrong address isn’t up/accessible (not just no web server), firefox will sit and spin for awhile before returning an error (not a 404 of course, since there is no web server to provide that).
DNS is the most likely cause (bank address changed, OP is getting a cached copy of the old address from somewhere)..
Yep. I get it... And stand corrected. But I still would bet on old Java or Flash choking the browser...