Taking a profile from XP to Win 7, flash stops working

I have been having this problem since firefox single digit versions.

if I use a fresh install of firefox portable on win 7 with portable flash, it works just fine, but if I take a frequently used firefox portable from win XP, flash player just refuses to work and freezes my browser or makes it extremely slow.

I have all the plugins and settings all set for this profile, and simply copying my XP profile to a win 7 install will retain this problem anyway. what can I do to make the flash player work without creating a new profile?