You may receive a 7391 error message in SQLOLEDB when you run a distributed transaction against a linked server after you install Windows XP Service Pack 2 or Windows XP Tablet PC Edition 2005

When you run a distributed transaction against an instance of SQL Server, you may receive an error message that is similar to the following:

This problem may occur when one of following conditions is true:

• Microsoft Windows XP Service Pack 2 (SP2) or Microsoft Windows XP Tablet PC Edition 2005 is installed on the computer that initiates the distributed transaction.
• Microsoft Windows XP SP2 is installed on the remote computer that is running Microsoft SQL Server 2000, and that computer is linked to the computer that initiates the distributed transaction.

Note The Windows XP SP2 features and components are included in Windows XP Tablet PC Edition 2005.

This problem occurs for one or more of the following reasons:

• Microsoft Distributed Transaction Coordinator (MSDTC) is disabled for network transactions.
• Windows Firewall is enabled on the computer. By default, Windows Firewall blocks the MSDTC program.
  
  Note This problem may occur even when Windows Firewall is turned off.

Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base: To work around this problem, follow these steps on the computer that Windows XP SP2 is installed on:

1. Make sure that the Log On As account for the MSDTC service is the Network Service account. To do this, follow these steps:
   1. Click Start, and then click Run.
   2. In the Run dialog box, type Services.msc, and then click OK.
   3. In the Services window, locate the Distributed Transaction Coordinator service under Name in the right pane.
   4. Under the Log On As column, see whether the Log On As account is Network Service or Local System.
      
      If the Log On As account is Network Service, go to step 2. If the Log On As account is Local System, continue with these steps.
   5. Click Start, and then click Run.
   6. In the Run dialog box, type cmd, and then click OK.
   7. At the command prompt, type Net stop msdtc to stop the MSDTC service.
   8. At the command prompt, type Msdtc –uninstall to remove MSDTC.
   9. At the command prompt, type regedit to open Registry Editor.
   10. In Registry Editor, locate, and then delete the following subkey:
       HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MSDTC
   11. Close Registry Editor.
   12. At the command prompt, type Msdtc –install to install MSDTC.
   13. At the command prompt, type Net start msdtc to start the MSDTC service.
       
       Note The Log On As account for the MSDTC service is set to the Network Service account.
2. To allow the network transaction, you must enable MSDTC. To do this, follow these steps:
   1. Click Start, and then click Run.
   2. In the Run dialog box, type dcomcnfg.exe, and then click OK.
   3. In the Component Services window, expand Component Services, expand Computers, and then expand My Computer.
   4. Right-click My Computer, and then click Properties.
   5. In the My Computer Properties dialog box, click Security Configuration on the MSDTC tab.
   6. In the Security Configuration dialog box, click to select the Network DTC Access check box.
   7. To allow the distributed transaction to run on this computer from a remote computer, click to select the Allow Inbound check box.
   8. To allow the distributed transaction to run on a remote computer from this computer, click to select the Allow Outbound check box.
   9. Under the Transaction Manager Communication group, click to select the No Authentication Required option.
   10. In the Security Configuration dialog box, click OK.
   11. In the My Computer Properties dialog box, click OK.
3. Configure Windows Firewall to include the MSDTC program and to include port 135 as an exception. To do this, follow these steps:
   1. Click Start, and then click Run.
   2. In the Run dialog box, type Firewall.cpl, and then click OK.
   3. In Control Panel, double-click Windows Firewall.
   4. In the Windows Firewall dialog box, click Add Program on the Exceptions tab.
   5. In the Add a Program dialog box, click Browse, and then locate the Msdtc.exe file. By default, the file is stored in the Installation drive:\Windows\System32 folder.
   6. In the Add a Program dialog box, click OK.
   7. In the Windows Firewall dialog box, click to select the msdtc option in the Programs and Services list.
   8. Click Add Port on the Exceptions tab.
   9. In the Add a Port dialog box, type 135 in the Port number text box, and then click to select the TCP option.
   10. In the Add a Port dialog box, type a name for the exception in the Name text box, and then click OK.
   11. In the Windows Firewall dialog box, select the name that you used for the exception in step j in the Programs and Services list, and then click OK.

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.