how can I fix my wall paper?

When I boot up my computer just for a second it will show my wall paper and then it goes to a blueish screen, I have tried to go into my properties but it will not let me change anything in themes, (everything is the same, all themes are gone. and I cannot open the desktop tab at all. It won't let me scroll through the pictures it will only let me change the color of the back ground. I use webshots for my screen saver and wallpaper, the screensaver is working just not anything else, please can you help me fix this? My program is windows xp
thanx