Okay, what am I missing? For some reason, when I set an absolute expiration
time it is always one minute longer for which I stated. I have tried it on a
few XP machines. Obviously there is a flaw in my logic I can not see. Here is
the code that you can paste into Global.asax:

   Private Shared _nextTime As DateTime

   Private Shared Sub MyCacheCallback( _
          ByVal key As String, _
          ByVal value As Object, _
          ByVal reason As System.Web.Caching.CacheItemRemovedReason)
       Try
           Dim firstTime As DateTime = Now
           Dim lastTime As DateTime = _nextTime

           'Check the difference
           Dim diffTime As TimeSpan = Now.Subtract(lastTime)
           _nextTime = firstTime.AddMinutes(10)

           System.Web.HttpRuntime.Cache.Insert("test", 1, Nothing,
_nextTime, _
           TimeSpan.Zero, Caching.CacheItemPriority.Default, AddressOf
MyCacheCallback)

           Debug.WriteLine(lastTime.ToString("HH:mm:ss") & " off by " &
Decimal.Truncate(CDec(diffTime.TotalMinutes)) & " minutes, next up: " &
firstTime.ToString("HH:mm:ss") & " --> " & _nextTime.ToString("HH:mm:ss"))
       Catch ex As Exception
           Debug.WriteLine("Error = " & ex.Message)
       End Try
   End Sub

   Sub Application_Start(ByVal sender As Object, ByVal e As EventArgs)
       ' Fires when the application is started
       'Insert something into the cache

       Dim firstTime As DateTime = Now
       _nextTime = firstTime.AddMinutes(10)

       System.Web.HttpRuntime.Cache.Insert("test", 1, Nothing, _nextTime, _
       TimeSpan.Zero, Caching.CacheItemPriority.Default, AddressOf
MyCacheCallback)

       Debug.WriteLine(firstTime.ToString("HH:mm:ss") & " --> " &
_nextTime.ToString("HH:mm:ss"))
   End Sub