In the Custom section of Set Program Access and Defaults (SPAD), the radio button to make the existing second browser default, disappeared. So, I cannot make my second browser (which is, Mozilla Firefox) default one, if wanted this way, but I have to go through more steps with Mozilla tools. How do I regain this option? The current default browser is Internet Explorer 7.
If reinstalling Mozilla Firefox does not restore the missing entry, try this:
Download firefoxreg.reg from the Attachments section of this article, and save the file to your Desktop. Right-click firefoxreg.reg and choose Merge. Click Yes when asked for confirmation.
Mozilla Firefox entry should now be available under the Custom section of Set Program Access and Defaults.