Windows 7 comes with IE9 and I don't think IE7 will run on that OS but IE8 will. Follow these steps to remove IE9 adn re-install IE8. Click Start and then type Cmd.exe in the Search box. In the list of programs, right-click Cmd.exe, and then click Run as administrator. Run this command twice from the command prompt.
FORFILES /P %WINDIR%\servicing\Packages /M Microsoft-Windows-InternetExplorer-*9.*.mum /c "cmd /c echo Uninstalling package @fname && start /w pkgmgr /up:@fname /norestart"