Retrieving pop3 maill

I have just migrated to Redhat 6.2 from Slackware. So far, so good -
until I tried retrieving mail from my ISP. After running netcfg and
setting up the ppp interface, I successfully connected to the Net and
was able to surf. Then, I tried setting up my mail client to retrieve
mail from my site (rickrosinski.com) which I have done for a long time,
successfully. The mail client (kmail) reports that my usr name &
password are incorrect - which is strange, since it was set up the exact
same way on my Slackware system. Then, I tried other mail clients. All
report the same error. Everything works in Windoze as it always did.

I am a newbie to Redhat, and have not mofified anything (except for what
I did with netcfg).

Please help!!!