When trying to follow a mailto:{email address} hyperlink in MSWord, a "Mail client not found" error message is displayed, which is correct because the Yahoo webmail is used for all email communication. Clicking OK opens a new Firefox tab with the Compose Yahoo e-mail page, which is great, but the "To" field is filled with a corrupted address composed of the correct "mailto:" address followed by the "firefoxhtml/shell/open/command" string. The "mailto:" links on the web pages and in the e-mails open in Yahoo mail as expected. I tried to Google this issue and found some similar issues on forums.mozillazine.org, but all the links to mozillazine.org end up on the 404 error page.