One nice thing I've found in these browsers is that you can check out the details of your present configuration easily.
simply left-click on the IP address that appears in the address field near the top of the browser window. When it is highlighted, type in "about:config" (w/o quotes)
scroll through the list...everything about your settings is documented, some in boldface.
Now, of course, being a student means I don't fully understand all of this, but you can modify from here, as well...and if by chance something has entered your system and changed things around a bit, you'll see it (ie. something changed your proxy settings, like malware can do)
I don't think IE has this easy-reader function...correct me if I'm wrong.
more info: about:config