The following simple little procedure can be used to check if a given report is already open.

'---------------------------------------------------------------------------------------
' Procedure : IsRptOpen
' Author    : CARDA Consultants Inc.
' Website   : http://www.cardaconsultants.com
' Purpose   : Determine whether a report is open or not
' Copyright : The following may be altered and reused as you wish so long as the
'             copyright notice is left unchanged (including Author, Website and
'             Copyright).  It may not be sold/resold or reposted on other sites (links
'             back to this site are allowed).
'
' Input Variables:
' ~~~~~~~~~~~~~~~~
' sRptName  : Name of the report to check if it is open or not
'
' Usage Example:
' ~~~~~~~~~~~~~~~~
' IsRptOpen("Report1")
'
' Revision History:
' Rev       Date(yyyy/mm/dd)        Description
' **************************************************************************************
' 1         2010-May-26                 Initial Release
'---------------------------------------------------------------------------------------
Function IsRptOpen(sRptName As String) As Boolean
On Error GoTo Error_Handler
   
    If Application.CurrentProject.AllReports(sRptName).IsLoaded = True Then
        IsRptOpen = True
    Else
        IsRptOpen = False
    End If
   
Error_Handler_Exit:
    On Error Resume Next
    Exit Function

Error_Handler:
    MsgBox "MS Access has generated the following error" & vbCrLf & vbCrLf & "Error Number: " & _
    Err.Number & vbCrLf & "Error Source: IsRptOpen" & vbCrLf & "Error Description: " & _
    Err.Description, vbCritical, "An Error has Occurred!"
    Resume Error_Handler_Exit
End Function