World of Warcraft & Restarting Computer Issue

Hello!
My little brother has ran into a problem with WoW and his PC, When he logs into his WoW account and joints a server 3 seconds into joining his computer restarts and the lights on his keyboard starts to flash.
Now I logged into another account for him and with my surprise it did not restart!
Would anyone have a clue to a solution and to what is causing it?
Regards,
Answer #1
check for latest wow patches,just to make sure i got it right,your saying
you logged into a diffrent account from HIS pc and it worked?
Answer #2
check for latest wow patches,just to make sure i got it right,your saying
you logged into a diffrent account from HIS pc and it worked?
Yep I logged in under my account and I could play fine, I find this a really bizarre case!
Answer #3
As stated, try patching, if it doesn’t work get the Blizzard “repair” tool. If THAT doesn’t work just go on the tech boards and you should have Blizz employees helping
Answer #4
also tryed logging in without any addons as many can bug wow and your cpu hit 100% hence pc reboot
Answer #5
Also try deleting the WTF folder, it will rebuild it when you load into your first account.
Answer #6
Try reinstalling it, (i know takes forever)