Do you have the lastest Bios, ver 207?Try this first: http://windows.microsoft.com/en-ph/windows7/open-the-power-troubleshooter(this is for Windows 7 but its the same in Windows 10)Try this also: In the power settings, set it to never to go into sle...
Is it a bluetooth mouse?My google search found that Windows doesn't allow bluetooth devices to wake up the computer. What happens if you wake up the computer by pressing a key?
Does it only happens in WoW?I googled it, and it seems to be a common error among a lot of WoW players. Try this: http://us.battle.net/wow/en/forum/topic/8569150180?page=6#111