N/A as yet. Good customer service is the best thing about NEC in my opinion. I like to use their laptops and PCs when working remotely, that way there's no issues with internet connectivity. I haven't had any problems with them since I started using them as my primary computer. Sometimes I do have issues with wifi dropping out, but that may be due to me not being close enough to an available router.
If you're looking for reliable products, then NEC is one of the companies you can always rely on