Shoutbox

i installed IE7 a few hours ago, but i noticed that a lot of websites did not turn out right - how they are supposed to appear...so i decided to uninstall it and change back to IE6...i did so successfully, but now everytime i type in a URL in IE6, it opens up a new tab in Firefox and opens the web page there...even if i click on the Homepage in IE6, it does the same thing...what happened? does anyone know how to fix this?

thanks for any help...