The OP is referring to the FREE Inbox.com (5GB). About 6 months ago, those who opt to sign up for inbox.com and take a FREE 5GB inbox must install a toolbar within their browser in order to activate the email account. This was never required before and as mentioned was implemented roughly 6 months ago. If you just accept all default settings, it changes your default home page and a few other settings.
I would recommend installing the toolbar for email account creation and once the account is created and you have successfully logged into it, from you computer, go to Start | Control Panel | Add Remove Programs and choose the inbox.com toolbar program listed in the add/remove programs Window. When going through the uninstall, you can select to restore your web configuration to it's original state.