As all we know that some websites illegally modify your registry editor and set their website as default home page, for stop this activity you can use this technique.To enable this technique you had to follow the following steps
1. Right-click on the Internet Explorer icon on your desktop and select "Properties".
2. In the "Target" box you will see "C:\Program Files\Internet Explorer\IEXPLORE.EXE".
3. Now by adding the URL of the site to the end of this it overrides any
Homepage setting in internet options:
"C:\Program Files\Internet Explorer\IEXPLORE.EXE" www.shareordie.com
In this way you can prevent your homepage from being changed.