[error 1603?]

I click the top right and still popping up with 1603

[error 1603?]

I have had paint.net for my old computer now when i try it gives me "error 1603". I'm really upset because this is one of the best computer painting tools, please tell me whats going on because when i go to the web ( http://www.dotpdn.com/downloads/pdn.html) although i can get the paint.net down-loader every time i try to download paint.net it doesn't work, even if i stop my fire wall it does nothing I'm really upset please if anyone reads this please tell me how to download it bypassing "error 1603"

I'm really upset, i have everything needed, windows 7, great internet reception yet it keeps failing every time i try it gives error 1603