Mail & .mac password

[birgit rhoads]

Using Apple Mail.  I very often am asked to give my password for my 
.mac mail account.  I enter the password and it is rejected repeatedly. 
  I re-enter the password in my .mac account and it is still rejected.  
Is this a problem with the .mac site?  I am getting my mail on .mac 
today, so their mail is not down.  Just cannot download it?

Anyone know why this occurs?

Birgit