Okay, to start this off, I've had SL on about six different computers over the course of seven years (2011).
Any computer I've tried to play SL on goes through the same diagnosis:
I download the game and enjoy it immensely over the course of several months.
While I'm playing, a black box with white text blinks into existence and then closes itself before I can read it. This usually happens several times over the course of a couple weeks.
My computer starts randomly turning off while SL is running. No bluescreen, just, *boop*, like someone flipped the off switch without my knowing.
Random shutoff extends to even when SL isn't running. First maybe once every six hours or so, but increases in frequency, worsening until it shuts off every ten minutes.
I have to wipe/replace my computer.
For all these computers I used Windows. Some earlier computers were on Vista, but I now use Windows 7. My computers, save for my laptop which has since died, have always been a frankenstein of old and new parts. Is that the problem? Or am I getting a virus though SL somehow? What can I do to fix this and allow me to enjoy Second Life without putting my computer at risk.
I don't know if it would be useful, but here is a screencap of my computer specs. This is a computer that I've had to wipe due to my latest SL endeavor.