[exim] tcp port smtp not found

Hi all,

after install the brand new debian sarge the exim package gives me the
following error that i'm unable to solve:

tcp port smtp not found

I've realized that the "services" file is readable and contains an entry
at least with the smtp reference to the 25/tcp port, but this seems not
to be enough.

Can anyone help me solve this issue or point me in the good direction?

TIA,
BR,

jonathan