hey drevil, thank you for your reply!
i have figured out the problem. its not a persistent pp cookie that try to force me.... (that was my seconde guess..). just do not change the language for pp from english to another one (german in my case) before you send the form from nrns>pp. you can later change the language direct on the pp-checkout site. otherwise i get allways forced to login before i pay or have to open a pp acount while cc transaktion. works with ff and ie.
kindest regards
-s