Anyone with problems after 6.3 upgrade has downgraded to 3.1 and then upgraded again?

[cancan]

I was wondering if anyone with problems after 6.3 upgrade has downgraded to 3.1 and then upgraded again. This because I didn't have any problems with 6.3a but now I do with 6.3b (A please insert valid card message every once in a while). I was thinking about downgrading to 3.1 and then doing all the upgrade again just to see if the problem get fix. But before doing it I would like to know if someone has done it.

Thanks!