Why is Handcent all of a sudden not working on my phone?

[AC Question]

When I got my phone a good while back I added handcent for texts. It also let my yahoo messenger messages come through. The other day the yahoo messages stopped, so I thought I would uninstall and reinstall it. That didn't work, now I get a message "The application Handcent SMS (processcom.handcent.nextsms) has stopped unexpectedly. Please try again" Then force close. I tried to uninstall and reinstall again and didn't work. I tried resetting factory settings and installing and same.