weird dual-monitor issue

i'm not exactly sure why this was happening, but when i tried to watch movies(using two monitors) via VLC, WMP, etc., the movie would play like crap and/or not work at all

I'm pretty sure that the reason is because of resolution issues coming from one monitor being a 21" widescreen and the other being a 19" regular monitor

anybody have any ideas on how to get this to work or should i just buy another monitor that is the same size at my widescreen?

tell us a little more about your setup. computer? gfx cards? software/drivers? etc, etc.....