Dunno if anyone has Sonic Mega Collection Plus, but unlocking Sonic 3 & Knuckles is driving me up the wall. I swear I've started up each of those games thirty times today alone, but it's meant to unlock at twenty times each. Does this always happen?
I don't own the game, but did you wait until the title screen of the games came up? That's what one of the solutions on gamefaqs says.
I might not have gone far enough into the title screens' little animations, but it always announced to me that it was saving my data.
Weird. Wish I could be more help, but keep trying, I'm sure it will unlock eventually. :<
I find online friend's birthdays hard too, because I'm never quite sure what to do ... I always want to do more than just say "Happy birthday!", but I can't give them presents or a card. I drew something for a friend once, but I'm a really bad drawer.