Windows Mail asking for user id & password

Hi, I've been using Windows Mail since I got Vista, with no problems. A few
days ago it started asking me for my user id & password, but every time I
enter them it comes up with an error message:
Account: '', Server: '', Protocol:
POP3, Server Response: '-ERR [AUTH] invalid user/password', Port: 995,
Secure(SSL): Yes, Server Error: 0x800CCC90, Error Number: 0x800CCC92""

I have a free yahoo email account, which I can still access via internet
I have tried deleting my account and adding it again after a re-start, have
made sure that the "my server requires authentication" isn't ticked, and I
also turned of my anti-virus scanning for emails (Norton) all to no avail.
My server port no's are 587 & 995.
I then changed them to 465 & 995, and now get the error message:
""Your server has unexpectedly terminated the connection. Possible causes
for this include server problems, network problems, or a long period of
inactivity. Account: '', Server: '',
Protocol: POP3, Port: 995, Secure(SSL): No, Socket Error: 10053, Error
Number: 0x800CCC0F"

What now please??

My server port no's are 587 & 995