Some adware/malware/etc sets the desktop/taskbar shortcuts to open certain pages automatically instead of your homepage. Delete and re-create whatever web browser shortcuts you have, or just right click on them, select properties, and see if there's any flags set to open certain pages in the "Target" field. It should be something like "C:\Program Files (x86)\Google\Chrome\Application\chrome.exe", if there's any other junk in there, remove it.