issue with Display Property

Hi, I am having issues with the display properties for my Windows XP. I turned my computer on and the screen resolution had been reduced to 800x600 with the lowest display quality. This has never happened before. I tried to return it to the normal settings that I always have, yet there is no option for me to do so. It continually tells me that my settings are on very low and that I may be able to change it, yet when I attempt to, it does not allow me. I'm not certain what could be causing this to happen. I need to go into safe mode now in order for the image to appear properly, but I am still not able to figure out what is causing my screen display to not allow me to change my settings.

Hopefully someone can help. Thanks.