Check what video driver your running. Ensure you have the correct setups. As far as resolutions, follow the xorg wiki (there are many, but you should be good to go by following the Sabayon or Gentoo ones). Your going to have to edit your xorg.conf. Its quite possible that all your issues are being caused by conflicting, or improper video setups. If your on ATI, I feel for you, because they truly hate linux. However, if your on NVIDIA or Intel, your in luck.