According to reports stemming from Japan (and now across the globe), Playstation Vita units have been overheating.
While charging, the system becomes overheated, leaving the PS Vita completely useless. While the 23 Japanese reports and 8 reports abroad are hasty to point the blame at a manufacturer default, Sony isn't backing down.
According to Sony, it's not a manufacturer default at all. In fact, they believe it to be from foreign material or liquids entering the charging slot.
The issue is being researched however, so the truth will soon be told.