OK ... I think I finally found the answer to your problems ... See below and follow exactly:
Note this was from this site:
http://www.lockergnome.com/win...n-internet-explorer-7/
Wow this was a tough one. Ok if you installed IE7 with your Windows XP install your basically screwed, unless you?re feeling frisky.
If you upgraded to IE7 from IE6, you can uninstall IE7 and then install Yahoo Toolbar for IE (for Yahoo) or Google Toolbar for IE (for Gmail).
The solution - walk over to a PC running IE6 and Yahoo Toolbar. Copy the following directories to a USB drive:
C:\Program Files\Yahoo!\common
C:\Program Files\Yahoo!\setup
(The setup folder may be optional - I got it to work fine so I didn?t tweak any more)
open up Notepad and insert the following - and save as ?IE7-Yahoo fix.reg?
Windows Registry Editor Version 5.00
[HKEY_CLASSES_ROOT\mailto]
@=?URL:MailTo Protocol?
?EditFlags?=hex:02,00,00,00
?URL Protocol?=?"
[HKEY_CLASSES_ROOT\mailto\DefaultIcon]
@=?C:\\PROGRA~1\\Yahoo!\\common\\ymmapi.dll,-202?
[HKEY_CLASSES_ROOT\mailto\shell]
[HKEY_CLASSES_ROOT\mailto\shell\open]
[HKEY_CLASSES_ROOT\mailto\shell\open\command]
@=?rundll32.exe \?C:\\PROGRA~1\\Yahoo!\\common\\ymmapi.dll\?,MailToProtocolHandler %1?
Import the registry after copying those files off of your USB. You can test it quickly in IE7 by typying ?mailto:? in the address bar. It worked for me on 2 different computers so it should work for you. If you?re looking for the Gmail registry settings do what I did and export the .reg from a working IE6-Google Toolbar installation. (with Gmail as default email)
Blame Yahoo and MS for doing this - they both want us to either use their email exclusively (MS) or pay $20 for Yahoo Premium, so that it will work with Outlook Express