Thanks for the tip but..
I've had a look in the admin and the maximum timeout for the session variable is currently set at 2 days and the default timeout is set at 45 minutes so shouldnt that work just by default?
The full line of code i am using is:
<cfapplication name="xxxxxx" sessionmanagement="yes" setclientcookies="yes" sessiontimeout=#CreateTimeSpan(0,0,45,0)# />
Also the cookie timeout is set to 20 minutes, could that be part of the issue or could there be something else that is causing the problem? The setting i am adding is in an application.cfm file rather than application.cfc as it was coming from an old version of coldfusion, also HTTPOnly is checked and so is '
