New ODBC issue Access 2007 - vba

Question

I have an MS Access 2007 front end to a MS SQL Server 2008R2 back end.
I've got a query that's part of a loop, and it's suddenly started generating Run-time error '3146': ODBC--call failed. errors on one query as the loop itterates. Oddly, it's not the first iteration. EDIT: When I say suddenly, it's been running like this just fine for several months (probably since March).
Set db = CurrentDb
db.QueryTimeout = 480 'thought there was a timeout issue, so set this very high
Set SupvRS = db.OpenRecordset("SELECT DISTINCT tblProcessors.Supervisor, tblProcessors.SupervisorEmail " & _
" FROM tblProcessors INNER JOIN (tblAuditPr INNER JOIN tblAuditPr_A ON tblAuditPr.PrAudit_ID = tblAuditPr_A.PrAudit_ID)" & _
" ON tblProcessors.Processor = tblAuditPr_A.Processor" & _
" WHERE tblProcessors.Supervisor IS NOT NULL " & _
" AND tblAuditPr.EndDate BETWEEN " & GetSQLDate(Me.txtFrom) & " AND " & GetSQLDate(Me.txtTo) & _
" AND tblProcessors.Processor<>'Default Processor' " & _
" AND tblAuditPr_A.Answer Not In ('NA','NF')" & _
" AND tblAuditPr.Status = 'Submitted'")
Do While Not SupvRS.EOF
'Send Supervisor Email
Attachment = PARG.GenerateAuditReport(SupvRS.Fields("Supervisor"), parSupervisor, Me.txtFrom, Me.txtTo)
Set EmailRS = db.OpenRecordset("SELECT * FROM tblProcessors WHERE Supervisor = " & GetSQLString(SupvRS.Fields("Supervisor")))
If EmailRS.EOF Then
Err.Raise -234923, Description:="Cannot find tblProcessors record for " & SupvRS.Fields("Supervisor") & "."
End If
If IsNull(EmailRS.Fields("SupervisorEmail")) Then
MailTo = <redacted>
Else
MailTo = EmailRS.Fields("SupervisorEmail")
End If
Set EmailRS = Nothing
Mailer.AddMailDocument MailTo:=MailTo, _
Subject:=Subject, _
Body:=Body, _
Attachments:=Attachment, _
From:=<redacted>
'Iterate processor emails if requested.
If Me.chkProcessor Then
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
'----------------------------------------------------------------------------------------
'ERROR occurs here, but only after several supervisors have successfully passed through
Set ProcRS = db.OpenRecordset("SELECT DISTINCT tblProcessors.Processor, tblProcessors.ProcessorEmail FROM tblAuditPr" & _
" INNER JOIN (tblProcessors INNER JOIN tblAuditPr_A ON tblProcessors.Processor = tblAuditPr_A.Processor) " & _
" ON tblAuditPr.PrAudit_ID = tblAuditPr_A.PrAudit_ID" & _
" WHERE tblProcessors.Supervisor = " & GetSQLString(SupvRS.Fields("Supervisor")) & _
" AND tblAuditPr.EndDate BETWEEN " & GetSQLDate(Me.txtFrom) & " AND " & GetSQLDate(Me.txtTo))
'----------------------------------------------------------------------------------------
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
Do While Not ProcRS.EOF
If Not IsNull(ProcRS.Fields("ProcessorEmail")) Then
On Error Resume Next
Attachment = PARG.GenerateAuditReport(ProcRS.Fields("Processor"), parProcessor, Me.txtFrom, Me.txtTo)
If Attachment <> "" Then
MailTo = ProcRS.Fields("ProcessorEmail")
Mailer.AddMailDocument MailTo:=MailTo, _
Subject:=Subject, _
Body:=Body, _
Attachments:=Attachment, _
From:=<redacted>
Else
Err.Clear
End If
On Error GoTo 0
End If
ProcRS.MoveNext
Loop
Set ProcRS = Nothing
End If
SupvRS.MoveNext
Loop
As noted in the code, the error occurs on an inner loop that successfully executes for other supervisors. It does consistantly break on one particular individual. Using the GetSQLString and GetSQLDate functions (returns ' delimited, double '' when necessary, pretty strings, and # delimited dates, respectivly, for passing Access queries through to SQL Server) in break mode, I duplicated the exact query that was giving me problems in an Access query. It returned a timeout error, but changing the database default timeout (and closing/opening the db) didn't resolve the issue. I pasted the exact same query into SSMS (replacing the # date delimiters with ') and it executed just fine there (taking about 1:30-2:00 to execute each try).
Taking a pause in typing up this post, I put some error trapping in to see if I could get the actual error message SQL Server was returning, when it ran without error. To me, that indicates that it is likely a time out issue. Anyone have a more educated guess as to what it actually is, or a suggestion on how to make the query more efficient so it doesn't time out?