Yeah, I upgraded one of my sites to v2.7. I sent a friend invite to myself at another email address and username...got the email and clicked the link. Took me to the login page and I was able to log in after receiving the activation email, that part was all normal...BUT when I logged out and then logged in as the sender of the invitation, it said "you can not send an invitation to yourself"...when I never sent one to "myself". The invitation I sent was to an alternate login with different user name and email and everything. Must be your installation...but I have reported my "bug" (and the bugs section is working now).