Speed Up Refresh Of External Data

I am having some issues using 'refresh all' to update my excel spreadsheet. Basically, it doens't seem to like doing anything greater than 65 queries before it gives me the error "Too many client tasks".

I've written a macro that updates all spreadsheets seperately, but this takes forever (I have approximately 250 worksheets within this workbook). Is there a way to speed this up? I believe the most time consuming part is establishing the connection to the access database. Is there a way to establish the connection to a database, and keep it open until all data has been updated?

Below is the code I am using:


Sub RefreshAll()
Dim e As Double
Dim sht As String
e = 1
Application.ScreenUpdating = False

Do
Sheets("All ESNs").Select
Cells(e, 1).Select

sht = ActiveCell.Value

Sheets(sht).Select

Selection.QueryTable.Refresh BackgroundQuery:=False

Sheets("All ESNs").Select

e = e + 1

Loop Until IsEmpty(ActiveCell)
Application.ScreenUpdating = True
End Sub
"All ESNs" refers to a worksheet that contains a list of all serial numbers. These serial numbers correspond to the worksheet names.