The Microsoft Exchange System Attendant service may not come online if the RootVer registry value is invalid on a server that is running Exchange Server 2003

The Microsoft Exchange System Attendant service may not come online on a server that is running Microsoft Exchange Server 2003 in a Microsoft Windows 2000 active/passive cluster. Additionally, events that are similar to the following may be logged in the Application log:Additionally, you may experience the following symptoms when this problem occurs:

• The Microsoft Exchange Information Store service may not start.
• The store databases may not start.
• The Post Office Protocol version 3 (POP3) service may not start.
• The Internet Message Access Protocol version 4rev1 (IMAP4) service may not start.

This problem occurs if the RootVer registry value is invalid.

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:

If the computer is running the Microsoft .NET Framework 1.1, set the RootVer registry value to 1.1.4322.0. To do this, follow these steps:

1. Click Start, click Run, type regedit, and then click OK.
2. Locate and then click the following key:
   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\ASP.NET
3. Double-click the RootVer value, type 1.1.4322.0 in the Value data box, and then click OK.
4. Quit Registry Editor.

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

This problem may also occur in the following scenarios:

• When you remove Active Directory from the domain controller, the ASPNET security account is removed. Therefore, the metabase update service may not be able to start. Additionally, several events that are mentioned in the "Symptoms" section may be logged in the Application log. To resolve this problem, reinstall Exchange Server 2003.
• When there is a permissions issue, several events that are mentioned in the "Symptoms" section may be logged in the Application log. To resolve this problem, run the Exchange Server 2003 Setup program by using the /domainprep switch, as in the following example:
  drive:\setup\i386\setup /domainprep