Startup Items - Not Always Hdden

[paulsalter]

Hi,
I have a minor problem, more annoying than anything else (Did search but couldnt find anything)

I have various items setup to automatically run upon login in, I have specified under the Accounts section, Login Items to run them as Hidden

iCal sometimes runs as hidden but other times just runs as normal
Mail always runs as normal, never hidden
Other Apps I have run as as expected, hidden in the Dock

Is there any reason why Mail/iCal might have trouble running hidden, There are no issues running the apps just this

Thanks for any help/info