I have gone to all the un install pages and cant find windows live mail to remove it. I am trying to install yahoo as my default mail program.

There is no uninstall for windows live mail. I have a toshiba with windows 7 and when I reply to a CL add or anything else, it goes there and never gets sent and then it keeps telling me  i have the wrong password. My boss has the same problem on his computer. what can I do?