Note that they may be running through xinetd. Xinetd is a program that does all the connection work for other programs.. once a connection is made, then the client program is started up. If nobody is logged in, there won't be any client copies of the program so DA will say it's not running. If you're not using xinetd, then the programs would be run as a daemon (standalone) and DA would show it as running even without anyone logged in.
If pop and sshd both work right now, then they're probaly using xinetd. If you an telnet to port 110, you should see a vm-pop3d header. If you see a header for another pop program, then you'll need to remove that other pop program to get vm-pop3d working.
John