Error: "Unable to cast object of type 'System.String' to type 'System.Byte[]" (4223486)

This error will affect most services. Below is an Example of the Exchange Store Manager Service but it is the "Exception Target Site: get_SourcePropertyConfig" that is important.

Event Type: Error
Event Source: Exchange Store Manager Service
Event Category: None
Event ID: 10
Date: 26.05.2009
Time: 16:20:36
User: N/A
Computer: Quest1234
Description:
MAPI.FolderCrawler.Manager: [2787286892-921715343-9-0x0] Failed to create the thread pool.
Exception Source: AfterMail Business Layer
Exception Type: System.InvalidCastException
Exception Message: Unable to cast object of type 'System.String' to type 'System.Byte[]'.
Exception Target Site: get_SourcePropertyConfig
Date and Time: 26.05.2009 16:20:36
Machine Name: QUEST01
IP Address: 192.168.2.1
Current User: Quest\ArchiveMgr_ESM
CLR Version: 2.0.50727.3082
Platform (version): Win32NT (5.2.3790.131072)
Application Domain: Archive Exchange Store Manager Service.exe
Assembly Codebase: file:///C:/Program Files/Quest Software/ArchiveManager/Archive Exchange Store Manager Service.exe
Assembly Fullname: Archive Exchange Store Manager Service, Version=4.1.0.376, Culture=neutral, PublicKeyToken=null
Assembly Version: 4.1.0.376