Well it seems the bug has infected Windows XP now!! Windows XP SP2 installed yesterday and about 100 patches. Now https:// does no longer work in Add Network Places!
'The folder you entered does not appear to be valid. Please choose another.'
ftp:// and http:// are accepted https:// is broken!
net use bails out with System error 67.
See also:
Mount box.net account in Windows Explorer « Techie Buzz
Maybe this hits the point (Excel modifies "https" to read "
http://s" - hohoho):
XL2002: "HTTP" Is Preferred to "HTTPS" as Default Prefix in Add Network Place Wizard