After having the issue myself I finally figured out how to turn off/set my screensaver. I tried all the ones in the form and they never worked I tried deleting the screensaver file but it did nothing. Every time and every way I tried to change it it would just go back to its normal setting.
After finding out that Windows 7 Starter didn't allow you to change anything like the background or the screen saver I found a program that would change my background. I downloaded it for my background and it worked great I was able to change my background to whatever I wanted.
But then I went back into this program and found out that there was also a screensaver option. When I changed the screensaver in this program it finally turned off. After downloading and installing the program, just right click the desktop and there will finally be a personalize option.
Select personalize and it will give you several options to change the background and an option to change the screensaver. Change it to what ever you desire and you will be good to go.