This may also happen intermittantly during the day depending on user load.
This occurs if the IIS application pools are restarted or reach the idle time-out.
by first taking a backup copy of the files and then editing the line:
with the following lines:
Implementing this solution/change will in most cases restart all of the application pools on the IIS server in question. The reason for this can be found here: http://msdn.microsoft.com/en-us/library/ms178683.aspx
Atrun time, ASP.NET uses the Web.config files to hierarchically compute a uniquecollection of configuration settings for each incoming URL request. Thesesettings are calculated only once and then cached on the server. ASP.NETdetects any changes to the configuration files and then automatically appliesthose changes to the affected applications, restarting the applications in mostcases. Hierarchical configuration settings are automatically calculated andcached again whenever a configuration file in the hierarchy is changed. The IISserver does not have to be restarted for the changes to take effect unless the processModel section has been changed.
'you cannot add this to an applications Web.Config but you can add it to the ASPNET.CONFIG file in the Framework directory'