Question: When working I will have multiple windows of file explorer open at a time. If I than start working on something else and leave those windows open in the background, they will close themselves leaving only one of them open. I have tried going into task manager and restarting file exploiter and that didn't fix it. i am running Windows 10 pro. Does any one have any ideas on how to fix? 

Thank you!

Answer: 
If there's a network glitch, where a local Windows Explorer senses that a Network Share is no longer available, the OS WILL close Windows Explorer which was previously viewing said share. No error, no warning. 100% frustrating. Most users would prefer seeing an error with a REFRESH / RETRY option.
If it is happening to mapped network drives and you have the drive set to "replace" I can confirm this is the case. Each time you modify a policy and the group policy updates it drops the map drive and remaps. If you set to update this does not happen. I hadn't had this issue and I have been working heavily on the "printer nightmare" and notice this was happening after I would make a change to Group Policy.