It did not used to do this, in fact I was just using it last week, I kept it plugged in. I just rearanged my desk which included tidying up the wires, I unplugged everything. Now when I plug the n64 converter into any usb port it causes my computer to turn off. My USB mouse does not do this so is this a sudden problem from within the device?

N64 converter?

Did it install the software? Could it be a problem with that?

http://www.gearzap.com/media/catalog/product/n/6/n64-controller-to-usb-adapter-2.jpg I assume.

nope this http://www.videogamecentral.com/product_images/p/132/ps2-n64-to-usb-controller-converter-adaptor__69829_zoom.jpg

But in black.

Have you tried uninstalling the drivers then reinstalling them?

Turn off? Turn off as in shut down or turn off as in just turning off with no warning?

Have you tried plugging it into a different computer and seeing if it does the same? Maybe it's damaged on the inside and shorting your computer out

Have you tried unplugging all peripherals and disconnecting anything extra internal you don't absolutely need? Maybe you're close to the max juice your PSU can deliver and it's pushing you over. (doubtful)