You are working for a company, your system admin has set the HomePage for Internet Explorer to the corporate website and you don't have the administrative rights to change it.
Don't worry, you can still change your default page on Internet Explorer. All you need is a little registery hack.
Go to HKEY_CURRENT_USER -> Software -> Microsoft -> Internet Explorer -> Main
When you click on Main, you will see a set of keys on the right of registery editör
Right-click on Start Page and click Modify
Set the Value data to the address you want and click OK
Now you should have your default website changed.
Hope this helps someone.