Um now I'm kinda lost.
When you go into you connections and manage existing connections lets start there.
First: delet any SPRINT PCS #777 you have.
Second: click new.
Third: Name it Sprint PCS modem is cell line. Click next
Fourth: Enter #777. Click next
Fith: My connection page leave blank. Finished
Now start your internet. A window will pop up asking for username/Password again leave it blank and just click ok. You dont need a username/password with sprint.
Sorry about the 123 but its easier for me to exsplain when I do it like that. Not implying anything about you.