Check out: http://www.monitorworld.com/
Find out what model monitor you have, and check it vs. their database. If you can't find it there, do a Google search, and you're likely to find it.
Make sure your details match up.
I know I've had many problems like what you speak of.
There is also a way to shift through different resolutions dynamically using a certain combination of keystrokes, but I don't remember what they are. A forum search may turn up something on that.