I have a Dell 20" ultrasharp that I use with my macbook while I'm home and from time to time when I plug in my laptop the resolution will be great, 1680x1050 and crisp and other times when I plug it in, my resolution seems to be lacking. The desktop icons are larger, firefox takes up the whole screen instead of just a portion like other times. Anyone know what's going on? I've tried googling and I'm kinda at a loss. Not really sure what's going on because I'm not doing anything differently.