I think my husband and I had the same issue, Chrisash. He had set up PStars on my computer for himself, then when I later tried to create an account it would give me the error you mentioned getting. We tried everything including uninstalling and when that didn't work checking the registry to see if there was something left over.
Finally, we figured out what to do, and I think the solution is what rookette is referring to. We use XP so I don't know if this will work with other Operating Systems. What we did was created another user profile on the computer (you know, so that two or more people can use the same compter, but have different logins). There I set up PS again and was able to sign up for my own account with no issues. I then got rid of the separate user profile and returned to my original one and was able to log into PS, again with no issues.
Hopefully this helps.
