Computer came and keyboard and mouse would not work after going to sleep. Several hours of calls to dell support and I convinced them it was a software issue. They said software people would call me but I would have to pay as it was not covered in two year "on site" warranty. Sent it back and received another, exact same problem. Returned it. Looked on internet and found several sites saying it is common problem,  with  dell sites saying it might be fixed by obtaining different bios and drivers. Would you buy a new car, take it home and when it did not start expect to have to pay the dealer to repair it? Amazon tried to help but dell apparently unimpressed with amazon. Amazon suggested I pay for software help or even take it to a repair shop and amazon might pay for it.