I have no idea what the show was, so I may not be much help, but I had a girlfriend once who watched a very "chick-flickish" type series that kind of revolved around racial tensions. There were two main women characters, one white and one black, who had been friends since childhood. I wouldn't say the show was completely based on rotating between two eras, but every show was full of flashbacks from their time as adults to their time as kids.
I really hated the show (too after school special for me), so I don't know the name, but it may jog someone elses memory.