This article was sent my way and looked pretty serious and possibly commonplace.  There is a hotifx available here (more details here) no hotfix for the problem (yet), but and there is also a manual work around at the end of the article.

http://support.microsoft.com/kb/932599

SYMPTOMS

After you apply a version of Store.exe that is later than 06.05.7651.26 on a computer that is running Microsoft Exchange Server 2003, you experience the following symptoms:

You can no longer mount any of the Exchange databases.

The following events are logged in the Application log:
Event ID 9519

Event Type: Error
Event Source: MSExchangeIS
Event Category: General
Event ID: 9519
Date: date
Time: time
User: N/A
Computer: ServerName
Description: Error 0x89a starting database "First Storage Group\Mailbox Store" on the Microsoft Exchange Information Store.
For more information, click http://www.microsoft.com/contentredirect.asp.
Data: 0000: 46 61 69 6c 65 64 20 74 Failed t
0008: 6f 20 63 6f 6e 66 69 67 o config
0010: 75 72 65 20 4d 44 42 00 ure MDB.

Event ID 9518

Event Type: Error
Event Source: MSExchangeIS
Event Category: General
Event ID: 9518
Date: date
Time: time
User: N/A
Computer: ServerName
Description: Error 0x89a starting Storage Group /DC=com/DC=domain/CN=Configuration/CN=Services/CN=Microsoft Exchange/CN=Org Name/CN=Administrative Groups/CN=AdminGroupName/CN=Servers/CN=ServerName/CN=InformationStore/CN=First Storage Group on

CAUSE

This problem may occur if the Microsoft Exchange Information Store service experiences an ecAmbiguousAlias error when enumerating the groups and users that are assigned permissions to the store databases objects in Active Directory. The error occurs when a security identifier (SID) cannot be resolved to a single user. In this scenario, the SID is present in the security descriptor of the database object that will not mount. The SID cannot be resolved to a single user if one of the following conditions is true:

•The SID is for a well-known user or group, and more than one domain exists in the forest. Therefore, duplicate objectSID objects are created.

• Two or more of the following objects have matching or conflicting values:
• objectSID
• msExchMasterAccountSid
• sIDHistory

These three attributes must be unique within the forest.

More information can be found here KB932599 and more information on the DST patch can be found here KB926666.

UPDATE 2/13- the product team has posted some more information about this and other DST issues here.