Poser 5 authorized without problem on my XP system. Q#1: when you re-authorize, does Poser 5 reach the screen where it says that it accepted the response code? That is, does it seem like it did authorize, but it is only when you quit, and then restart Poser that there is a complaint? Q#2: Did you receive the automated e-mail from CL, that includes the response code? [another way of checking that the registration process completed okay]. Q#3: does the problem only occur after RESTARTING XP? Q#4: When you select "Help/About Poser", does it show your correct serial number and name? -- ToolmakerSteve