"Cannot run with other SMB/CIFS/Microsoft networking servers on the same machine. Error Code: 48"

There are two causes of this error:

1. OS X 10.7, Lion, and the Firewall

In Lion, the built-in Firewall can cause ADmitMac or DAVE to report this error on installation.  This is a bug in the Firewall that has been reported to Apple.  To work around the issue, launch the System Preferences and click the Security & Privacy pane.  On the Firewall tab, stop the Firewall, then reboot the Mac.  You should then be able to install ADmitMac or DAVE.

2. Windows File Sharing

If SMB (Windows) File Sharing is active, you will need to turn it off before installing ADmitMac or DAVE.  To do so, launch the System Preferences and click the Sharing pane.  With File Sharing selected, click the Options button, then uncheck the "Share files and folders using SMB (Windows)" checkbox.  After restarting the Mac, you will be able to install ADmitMac or DAVE.