Kasperksy Internet Security 6.0 blocking email ... any ideas?

I installed KIS 6.0 on a WIN98SE box a few days ago.

When I first boot up, email (Eudora 5.1.1 - very old version) works
fine.

After a varying amount of time (a few minutes to half a day), the
email no longer works ... the little ball just spins and spins. I've
tried fiddling with the email settings in KIS (both anti-spam and
email-virus). Nothing will cure it , even turning those services
completely off.

Email did work when I disabled KIS entirely (I'm behind a NAT router).

When I reboot, it works again ... both in and out.

Any ideas?

Bob

(change younger to older to reach me by email)