cell phone with its own mind.

[Trek420]

just checked, the phone itself has about 800Mbyte free.

Sorry for the late response. In general smart phones like about 10% available memory. Phone has 16gb capacity, at least 1.5 go free. When it's less than that I find exactly what's happening to you occurs; phone gets poltergeists, stuff vanishes Etc. I'd start by backing it up and then delete stuff.

Source; work in advanced iPhone tech support.