default mail client not installed
 

All of a sudden when I click on an email link in IE7 on a web page I get this
error message "default mail client not installed". Running Windows XP Home
sp2, Outlook 2003, IE7

WHAT I'VE ALREADY TRIED:
1) I reinstall IE7 and it worked, but the first time I re-booted it stopped
working again.

2) I went into IE7\Tools\Options\Programs and changed to Outlook Express,
then back to Outlook.

3) I went into Explore\Tools\Options\File Types and checked and re-set the
URL:MailTo Protocol.

4) I went into the Registry\HKEY_CLASSES_ROOT\mailto and re-created the URL
Protocol.

5) I ran Detect & Repair in Outlook but it did not fix the problem.

I don't see anything different before and after re-boot, but after re-boot
it doesn't work.

help!!!