I experienced many problems while being dialed in using the default
kppp that ships with redhat 6.2.  The most common occurrence was kppp
reporting that pppd died unexpectedly.  This happened often,
occasionally requiring a re-boot of the system to get it to hang up
the modem and dial again.  Some times it occurred imediatly after
establishing a connection.

I found one obscure reference on a newsgroup stating that kppp 1.6.24
has known issues like this and that it is recommended to upgrade to
1.6.25.  I did and have not seen any problems with my dial-up connection
since.

I see no current upgrade to kdenetwork.  I had to perform a rather harsh
rpm command to override conflicts and upgrade my kppp.  An official rpm
upgrade from redhat for kdenetwork.rpm may help others in solving this
problem in a more efficient manner than I did.  Aparently kppp 1.6.24
isn't completely compatible with the pppd 2.3.11.

I apologize for stating how you should fix it.  I hate when people do that
to me!