It's a common problem with IE 7. Only upgrading will really fix it, although you aren't the first to have the problem, which leads me to believe that a recent windows update may have introduced this bug (which should be fixed on the next update).
Either use the latest IE (download link below), use another browser (I recommend FireFox), or set windows to update (hopefully there is a patch that will fix it).
Windows Internet Explorer 8: Home page
https://www.microsoft.com/windows/internet-explorer/beta/default.aspx