You install the May 2007 Cumulative Security Update for Internet Explorer (MS07-027), and then you try to open Windows Internet Explorer 7. After you do this, the File Download Security Warning dialog box may open, and you may receive the following message:
Do you want to save this file?
The File Download Security Warning dialog box also refers to the "navcancl" file name. After you close this dialog box, you cannot start Internet Explorer 7.