I'm not the expert on this, but I used to have the same problem (exit status 19/16 once "logging on to network"). The problem was the special logon method AOL uses, so I had to download "penggy" or "pengaol" in order to use dial-up with AOL. Worked fine after it installed.
Perhaps your ISP is the same? Try downloading the penggy, it is fast and easy to set up, so it won't hurt.
PS: if I'm right, you can click on "details" when it exits and you should get something saying possible bad password or logon.
Also, with some ISP's, you have to enter your username as "email@example.com" rather than just the username. Try doing that.