I was running up Visual Studio for an ASP.NET project when I got this error:
"Unable to make the session state request to the session state server. Please ensure that the ASP.NET State service is started and that the client and server ports are the same. If the server is on a remote machine, please ensure that it accepts remote requests by checking the value of HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\aspnet_state\Parameters\AllowRemoteConnection."
Mr. Google to the rescue and you have to start up:
Control Panel / Administrative Tools / Services.
Right click on ASP.NET State Service / Start
Refresh the browser and you're good to go.