You are having issues with your ATI card. Either the card or the drivers. It is best to try and install the right ATI driver. Go to this link to find out how to resolve this issue: http://www.linuxquestions.org/questions/history/366586.
This info is SuSE 10 and ATI x600 specific, but the procedure will work with other ATI cards.
"Mode Not Supported" means that the system is trying to get the video card to so something it can not do. SuSE has problems like this that require a reinstall of the driver. Do Not assume that because SuSE detected the right card that it installed the right drivers.
Please next time do a google search or search this forum prior to posting a new question. Chances are that someone has already asked this question before.
BTW: When you say "hanging" do you mean that the computer is non responsive or that it boots in the console? Diagnostically these are two extremely diferent symptoms that can mean two diferent problems.