My wife's computer did this a couple years back, ironically in XIV 1.0. Same thing, she could do other stuff fine, but fire up XIV and the computer would just turn off.

Wound up being the power supply, it finally just blew out instead of powering down. End result wasn't pretty either, generally when sparks and flames shoot out of the power supply, it will take other things with it.

Do you have a friend with a computer you might be able to borrow a power supply from to check? Beats spending the money outright for a new one, only to see the same problem and find out that component XXX is actually the one failing.