Domain mapping plugin - installed update now login pages don't work

Hi there,

I installed the update for the Domain Mapping plugin today. Since I've done that the login pages for all my mapped domain sites are not working. Whether I select thelogin page to be the "original domain" or "mapped domain", it still doesn't work. The login page appears but when you enter the username and password, the login page just reloads. Any suggestions as to what might be happening?