Default Bluetooth not Enabling on TyTN II

My client has a unlocked GSM HTC TyTN II phone, purchased directly from HTC. Factory installed ROM. I go to Settings > Connections > Bluetooth and click the Enable bluetooth checkbox. When I go right back in the checkbox is turned OFF-- it won't stay on. I have tried rebooting the phone several times. This just stopped working a week or so ago, before that Bluetooth was working great with a headset.

It seems like something is switching it off for me--are there any mutually exclusive settings or dependencies I'm not thinking of?