Parallels keeps deactivating itself

I installed Parallels 4.0 onto my hard drive, upgraded to Snow Leopard, not a problem.
I have now installed it onto Snow Leopard on my new SSD, and I activated it but it keeps deactivating itself.
It wants the activation code, I've already put it in once or twice already since the initial time!

Does anyone know why?
The VMs that I copied and pasted over seem to work fine, I opened them in Parallels on the SSD, and told it that they had been copied and not moved like it asked.

Kind Regards