I upgraded from Windows 7 to Windows 10 in my acer laptop. It is really slow and showed the error of DPC_WATCHDOG_VIOLATION all the time.
After going back to Windows 7 , I could not switch to Chinese language via Ctrl+ Space. The language bar was missing in the taskbar even if my keyboard setup looked good in Regional and Language. Thats really a nasty bug. I need to add something in the registry key and make it work. Not user friendly. :)