Occasional trouble with ALD Hotspot

I've had several patrons this month who have had issues getting access to the internet through our hotspot.  So far it's been two people on their own laptops, a boy with his Nintendo DS and another patron with a new cell phone.  It tells them that they are connected to our network but not allowed internet access.  With each patron I was able to help them gain access by closing out any windows that were currently open, reopening their browser and either choosing the home page or one of their favorites.  This caused their browser to find our hotspot splash page and they were able to proceed from there.  Not sure if there is a better solution to this but it's been a pretty quick fix for me.