cannot change video settings - new monitor

Hi, all.  Need some help here.  I just upgraded my monitor from an 18" LCD (running 1248x1024, I think) to a new 23" HD monitor (1776x1000).  Started up the game, and it runs in a seperate window with the bottom of the screen hiding under the windows toolbar.  I can move the screen around, but cannot maximize it.  I went to video settings, and almost all of the settings I could not change (I clicked on them, but nothing happened).  WIth the old monitor, it would use the full screen and I would have to alt-tab to get back to windows.  any thoughts on why this isn't playing nice?  The biggest thing is the little bit that is hiding under the windows toolbar; otherwise I think it would be okay.  I can move the toolbar to the side, but it still hangs over the display a little (likely the 1000 vs 1024 vertical resolution).  Anyway, any help is appreciated.  Thanks!