I've been having the same problem with Gmail. I use Firefox and it will show a blank screen and say done. Yet, if I switch to another browser like Opera, it loads up fine. It's gotta be in the cache. If all else fails, wipe the history of everything and to be sure and clear all the cookies. The same problem happened to my laptop, but now it works and I think it's because I cleared everything, including saved passwords. You might be using an autologin option from Yahoo that could be a contributor to the problem.
-Bossman