Got same problem and should be able to sort it when i get hom etonight.

I called sony and explained that 5 systems have my account activated and i need to free at least one.( for myself )

They said that if i give them the serial code for my current ps3 then they can deactivate all other linked ps3 to my account.

So i will post back tonight and tell you if it worked.

It damn well better or ive lost out on all my purchases.