Error: Check Activation and Error with deautorization

I installed ADE 4.5 on my PC. Every time I try to open an urllink.acsm I get the message: "Error! Check Activation". My PC ist autorized with my ID. I guess that the solution is to deautorize my PC and then to re-autorize it. Unfortunately, every time I try the deautorization I get the message "deautorization isn't possible. Try it later"... What can I do now? Thanks!