When you open a new tab in Internet Explorer 7, the about:Tabs page opens which contains information about tabbed browsing and lists available tab shortcuts in Internet Explorer. If you had enabled the Don’t show this page again checkbox and closed the tab window, every new tab opens with a blank page. Here is how to reverse the setting if you need to restore the about:Tabs page at a later stage.
Launch Regedit.exe and navigate to:
Right-click the value named ShowTabsWelcome and choose Delete
Exit the Registry Editor.