Resolution errors

i have just reinstalled my windows 7 and i never had this problem before but now i keep getting half a screen when i load and when i try to use the normal resolution 800x600 or 1024x768 or what ever i cant get a full screen and when i use the wide screen ones it doesn't look correct and the lettering is in bold and the people are stretched vertically \

help
destop res 1680x1050
i used this before as well