The following KB has recently been published http://support.microsoft.com/kb/951380 and a hotfix is available.

 

SYMPTOMS

When you run a discovery operation in Microsoft System Center Operations Manager 2007 Service Pack 1, and a cluster node is discovered, some computer properties may not be collected for the cluster node. For example, the DNS host name, the security identifier (SID) and the Active Directory organizational unit of the cluster node may not be collected. Therefore, some Operations Manager workflows may not function correctly. For example, if the DNS host name is not collected in an Operations Manager 2007 environment that has the Microsoft Exchange Server 2007 Management Pack applied, the following event may be logged:

Event Type: Warning
Event Source: Health Service Modules
Event Category: None
Event ID: 10720
Date: Date
Time: Time
User: N/A
Computer: ComputerName
Description:
The Backwards Compatibility mapper module was not able to start because discovery has not fully completed for this Health Service. This is a transient issue, the affected rule(s) will be unloaded and the Health Service will restart them when initialization is complete.

RESOLUTION

Hotfix information
A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.
If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.
Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site:

http://support.microsoft.com/contactus/?ws=support (http://support.microsoft.com/contactus/?ws=support)

Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.

Prerequisites
To apply this hotfix, you must have System Center Operations Manager 2007 Service Pack 1 installed.
Restart requirement
You do not have to restart the computer after you apply this hotfix.
Hotfix replacement information
This hotfix does not replace any other hotfixes.