Error: "Value cannot be null" reported in Event Viewer for FTIAttachmentWorker.exe (4303034)

Exception Source:      mscorlib
Exception Type:        System.ArgumentNullException
Exception Message:     Value cannot be null.
Exception Target Site: Enter
Date and Time:         3/7/2011 4:35:54 PM
Machine Name:          ServerName
IP Address:            ::1
Current User:          Domain\ArchiveMgr_Service
CLR Version:           2.0.50727.4927
Platform (version):    Win32NT (6.1.7600.0)
Application Domain:    FTIAttachmentWorker.exe
Assembly Codebase:     file:///C:/Program Files (x86)/Quest Software/ArchiveManager/FTIAttachmentWorker.exe
Assembly Fullname:     FTIAttachmentWorker, Version=4.4.2.165, Culture=neutral, PublicKeyToken=null
Assembly Version:      4.4.2.165

---- Stack Trace ----
   at System.Threading.Monitor.Enter(Object obj)
   at Quest.ArchiveManager.FullTextIndex.AttachmentIndexer.FetchAttachmentIndexerFile(Object aifObj)
   at System.Threading._ThreadPoolWaitCallback.WaitCallback_Context(Object state)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading._ThreadPoolWaitCallback.PerformWaitCallbackInternal(_ThreadPoolWaitCallback tpWaitCallBack)
   at System.Threading._ThreadPoolWaitCallback.PerformWaitCallback(Object state)

 

There may also be events in the Archive Manager Full Text Index service log file saying that specific index files cannot be removed during the indexing as well as multiple DW20.exe errors showing up in Task Manager.