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KB10104: Error 602 - port is already open

Summary: If you get an error 602 when you try to connect to the internet (port already open), there are several things to try.

SYMPTOMS

When you try to dial up, you get one of the following errors:

Error 602: The modem is being used by another Dial-Up Networking connection or another program. Disconnect the other connection or close the program, and then try again.

Error: port in use

CAUSE

There are several potential causes:

Other software, such as fax or telephony software, may currently be using the modem.
AOL is set up on the computer.
Rnaapp.exe is active in memory (Windows 95/98).
Quicken 2000 with Windows 2000 or XP sometimes ties up the modem.
Spyware, Viruses, Adware, and/or other Malware may be trying to use the modem.
Incorrect modem initialization strings.
Faulty hardware.

RESOLUTION

Before anything else, try rebooting the machine. Many times a reboot will reinitialize the operating system and the modem, thus resolving this issue. If this doesn't resolve the issue, or if this issue reoccurs:

Check to see if you have any other software running that uses your modem. Examples include SuperVoice and WinFax. If so, you may need to review your software documentation to keep this software from launching at windows startup.
Many times when AOL is installed on your computer, it may interfere with other dialers. If this appears to be the case, you may need to uninstall AOL, the adapters AOL set up, and reinstalling any Microsoft Windows adapters.
If you have Windows 95 or 98, check to see if Rnaapp.exe is running. You can do this by:
1. Press CTRL+ALT+DELETE to open the Close Program dialog box.
2. Click Rnaapp to select it, and then click End Task.
With Windows 2000 or XP if you have Quicken 2000 installed: The error can be caused by the Quicken Download Manager; Removing the modem and re-installing it may result in the modem working - for a single session. The permanent solution is to remove Quicken 2000, or disable the Quicken Download Manager. Please read this Intuit article for further information.
If none of the above works or does not apply to your situation, you may have Spyware, Viruses, Adware, and/or other Malware running on your computer. Please scan your computer with the latest Antiviral and Anti-Spyware software to help ensure that you are free of Malware.
In rare instances, this may be caused incorrect modem initialization strings. If you have NOT modified this string to repair other issues (i.e. disconnects or slow speeds), you can change it to a generic modem string.

In Windows XP:
1. Click Start => Control Panel
2. If the control panel has the heading: "Pick a Category" click "Switch to classic view" on the left.
3. Double-click "Phone and Modem Options"
4. Click the "Modems" tab
5. Highlight the modem, then click "Properties"
6. Click the "Advanced" tab
7. Under "Extra initialization commands," type "ATZ"
8. Click "OK," then "OK" again.
If you have another version of Windows or if you have changed this setting in order to correct an issue, please contact technical support for further assistance.
If all else fails, it is possible that you may have faulty hardware. You may need to take your computer to a repair technician for further assistance.

MORE INFORMATION

Microsoft Knowledge Base - Q158114 (http://support.microsoft.com/kb/q158114/)
Intuit Knowledge Base - KB ID 1935 (http://web.intuit.com/support/quicken/2000/win/1935.html)

Document reference number: KB10104