The release 2.1.4 of rhn-applet fixes some problems making rhn-applet nearly unusable on a default Fedora Core 1 setup:
- pop-up dialog asking for registration to RHN
- failure to handle HTTP(S) redirect on YUM sources
- failure to handle file:/// based YUM sources

Related bugs:
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=108737
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=109502

The new version has been tested successfully by a couple of people but more testing is needed.