If it's doing it from within VS but not from outside then you have configured the virtual directory incorrectly.
These things need to run in the root of a virt dir, and they need to be set to SCRIPTS ONLY.
You seem to have gone through the same stuff I did. Incidentally, my site shouldn't need any permissions - it doesn't access client side.
I know - IE security is a pain - and when you mix it with msccorcfg.msc it can come up with some dodgy decisions to say the least.
Ages ago (in the beginning) I was talking to a chap on Sourceforge who was writing a .NET layer to interact with OpenGL - so wicked graphics in the control ... only after he'd done loads of it didi he realise that he'd need persmissions to access the hdd.
Sos I've been a bit slow - I have been getting a bit of brain fizz and blurry eyes, and been desperate to get hold of info on ITemplate (hardly any anywhere).
I seem to have a bad habit of picking undocumented problems ( the last one was IIS Base Admin objects - recursing the metabase - nothing, anywhere, nowhere on the subject, minimal wishy washy interface brush over in SDK docs - nothing else anywhere. It'd be easier to write a new layer yourslef.)