can not get to my disply proporties

when I right click on my desktop it does not get me to the display propoties window. I also have problem with locking up when I close out some programs like AOL 6.0 . I have an ASUS A7V MB with an 800MHz Thunderbird and 128Mb of PC133 SDRAM (Kingston) memory. Any help would be greatly aprecciated. Thank you,
Jeff