Session Reset in ASP

I've seen that problem in some servers. The symptoms shortly are that after calling an asp.net page, the whole application is reset, so all the sessions are lost. I guess that it's due to some misconfiguration of the server, but I don't know the real reason.

The test is easy:
Create an asp page that sets some session variable, then display it (for example

<%
if isempty(session("start")) then
session("start")= now()
response.write "init session"
else
response.write "Started at" & session("start")
%>

Now create an aspx page, it doesn't need anything special, just something to start the .net engine.

Load the asp page, then load the aspx page. Now wait some seconds and reload the asp page, if it works, wait a little more, reload it several times, but in less than one minute the asp session will be reset, the whole application restarts.

The solution for you would be to disable the asp.net thumbnails until you can manage to fix the problem with asp.net