pop3 server keeps asking about username and password even though i have put the correct information

actually my mail was working fine on old pc. Now, i got the new desktop and i configured my same account on that pc. i imported all my emails and contacts from old pc. now, the problem is when i try to start windows mail on new pc it keeps asking me to enter username and password, i am not able to receive new emails. is it because my same account is still ON in old pc. i am very confused, would it solve my problem if i remove my account from old pc. i don't want to lose my emails. what should i do? i have configured my pop3 server correctly as it was on old pc.