Fixing laptop that keeps restarting after I shut it down

So my wife's dell laptop of almost 2 years started acting funny. It basically would not shut down. Of course, one of the things we think of is it a virus or malware. We do keep antivirus and firewalls on that laptop, but anything is possible. We first tried to go to a restore point to see if that will fix he problem. It did not. We also did a full antivirus scan and nothing popped up. Then we researched the action on different forums. It looked to be a hardware issue. I checked to see if the network adapter drivers were up to date. They were. The forums also described changing some stuff on the bios. I was reluctant to do this, but did it anyways. That did not fix the problem. At this point, I figured it could be an undetected new virus of some sort. My usual fix is reformatting the laptop and putting it back to factory settings. The other problem could simply that the network adapter just failed which in that case would simply need to be replaced. I reformatted the computer back to factory settings. Tried to shut it down, but it still restarted. Problem not solved. I would conclude that is hardware failure +++++Solution+++++++++ So by chance, I tried one last thing. I put the laptop into sleep. That worked. Then I put in hibernate. That worked. Then I tried to shut it down. That worked. Now the laptop works just as it did before. How odd. Anyway, I thought this might help someone else out and wanted to share. Good luck and cheers!