I'm almost wondering if there is a bug in Windows 8.1, because I see that both of you are having similar issues. If it is causing problems, I would revert back to windows 8 with your system recovery.
Are any of your computers under warranty? "Asking both people having problems in this thread". I'm a computer tech, and I would do troubleshooting by removing the hard drive, install a clean hard drive " spare drive" and install a clean retail version of Windows 8.1, and see if the problem comes up with a clean install. If the problem is not there, then I know it's a bad upgrade.
I've got 9 years of experience as a computer tech, and with my experiences, I hate buying preinstalled systems due to that there can be lots of problems with the software packages and Windows installation. With preinstalled systems, if you upgrade to a different OS, you lose recovery functionality, and would have to know how to reset the recovery drive in the WinRE environment. There are programs out there that can help with the process, but it causes issues because work arounds sometimes causes problems too.
I choose to build my own PCs, that way I know what's going in the system, and clean oem copies or retail copies, I rarely have issues with them. So I always try to do things to where I know it will work out of the box, and updates or upgrades won't break functionality. Yes, that's a Microsoft issue, since stuff isn't probably tested perhaps, but I tend to go the route I know there are no issues.
Sorry I don't have a fix, but this is a strange problem.