Personal hotspot unavailable intermittently, "contact your carrier"
Some cellular plans allow Personal Hotspot / Tethering, others do not. It's worth your friend checking with your cell provider whether it's allowed on the plan she's on and/or if there's a usage limit (highly likely) and that limit has been reached.

For reference, my old cell plan had 1GB of Personal Hotspot usage allowed and watching a couple of movies on the laptop using Netflix got through that real fast, so I upgraded my plan.