The Windows Club has released FixWin 2.0 for Windows 8, a Windows 8/ 8.1-specific edition of its portable PC troubleshooting tool. As before, the program lists 50+ common problems and symptoms across a range of categories: "File Explorer", "Internet & Connectivity", "Modern UI" and so on...
The Windows Club has quite a collection of freeware utilities: http://www.thewindowsclub.com/list-freeware-releases-from-the-windows-club
This one, in particular, might be a good general purpose tool for solving a variety of problems...