Microsoft KB Archive/824608

Knowledge Base

"NetBIOS Is Already Active" Error Message When You Start a Virtual Machine

Article ID: 824608

Article Last Modified on 10/28/2003

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APPLIES TO

• Microsoft Virtual PC for Mac Version 6.1, when used with:
  • Apple Mac OS 9.0
• Connectix Virtual PC for Mac 6.0, when used with:
  • Apple Mac OS 9.0
• Connectix Virtual PC for Mac 5.0, when used with:
  • Apple Mac OS 9.0

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SYMPTOMS

When you start a virtual machine in Virtual PC, you may receive the following error message:

A NetBIOS client is already active on this Macintosh.
When using Shared Networking, only one NetBIOS or Microsoft Networking client can be active at a time. Using Virtual Switch solves this problem.

For more information, see the Virtual PC manual.

CAUSE

This problem occurs under the following conditions:

• The Macintosh computer is running Mac OS 9.
• Thursby Software Systems DAVE is installed.
• The virtual machine is using Shared Networking.

DAVE establishes NetBIOS over TCP/IP when the Mac is started, and this will prevent the virtual machine from using the same NetBIOS under Shared Networking.

RESOLUTION

To resolve this problem, use one of the following methods.

Use Virtual Switch

To use Virtual Switch with the guest operating system on your virtual machine, follow these steps:

1. Start Virtual PC.
2. On the Virtual PC List, click the virtual machine that you want to configure.
3. Click Settings.
4. Click Networking.
5. Click to select the Enable networking check box.
6. Click Virtual Switch.
7. Click OK.
8. On the Virtual PC menu, click Preferences.
9. Click Virtual Switch.
10. In the Select Ethernet Adapter list, click one of the following options:
    • (Default)
    • Built-in Ethernet
    • Ethernet Slot
    • AirPort
11. Click OK.

The Microsoft Windows guest operating system must be configured to automatically obtain a TCP/IP address from a Dynamic Host Configuration Protocol (DHCP) server, and a DHCP server must be available on the network.

-or-

The Windows guest operating system must be configured with a static TCP/IP address that is different from the TCP/IP address of the Macintosh computer. For additional information about setting your Windows guest operating system to use DHCP or Static IP networking, click the following article numbers to view the articles in the Microsoft Knowledge Base:

314066 How to Enable Internet Connection Sharing on a Home or Small Office

237254 How to Enable Internet Connection Sharing on a Network Connection in Windows 2000

230151 How to Configure ICS to Use a Static IP Address

262227 Description of the Home Networking Wizard in Windows

For more information about using DAVE with Virtual PC, see the Thursby Software Compatibility FAQ. To do so, visit the following Thursby Software Support Web site:

http://www.thursby.com/support/faq/

Turn Off DAVE

You can also turn off DAVE before you start Virtual PC. To turn off DAVE, follow these steps:

1. On the Apple menu, click DAVE.
2. Click Disable NetBIOS Networking.
3. Click OK.

This procedure turns off DAVE, and Virtual PC is then able to connect to the network.

The third-party products that this article discusses are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, regarding the performance or reliability of these products.

Keywords: kbprb KB824608

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