I got all the way to the end where you are supposed to open the egg, did the thing to open the egg, and it didn't open. I spent days going back through every dungeon to try to trigger it but never could. I couldn't bring myself to replay the game and hope it worked this time.
I got the game the same year it came out and still have never beaten it because of that. Sounds like it was just a super glitchy game.
It ended up stuck on a wall, completely glitching the game. Reloading didn't help. My save was dead. I was devastated at the time :)