Your homepage could change because your computer is infected with spyware. Spyware/Adware both have the capabilities to change the setting on computers. The best thing to do is to run your virus program. Next you can run a adware/spyware removal program. There are several programs available, but three of the better ones are Windows Defender, CC Cleaner and LavaSoft Adware. Windows Defender and CC Cleaner are free. Windows Defenders also monitors your computer and stops adware before it can attach itself to your computer.