You don’t need to register again. The first Registration Key will be valid.
Either, you don’t have to download it again unless the file is corrupt.
Do you have any other antivirus installed right now in your system?
Do you use TeaTimer or other application that monitor the startup itens?
Which firewall do you have?

Did you shut down your spam killer?
Anyway, you could use the first Registration key, no problems. :wink: