Thanks for the DxDiag results, They show a couple things that should be looked into, and your description of how you've been trying to deal with the problems is also something I'd like to try and untangle.
First, the DxDiag results show that you're using a video driver for your nVidia GT 1030 that's over a year old. However, that card doesn't have the video encoding hardware that PD requires (called NVENC) so it isn't being used for producing at all. You can update the driver anyway, but it probably won't have any effect on how PD is working.
Take a look at this
chart. If you were to upgrade to any card with green shading on the right side, PD would be able to produce much faster than your CPU is able to do right now on its own.
The other thing that concerns me is the number of Windows Update-related failures shown in the last hundred lines of the results. It's not surprising to see PDR.exe there (BTW you do have the latest version of PD1

, but the other errors point to problems with how well Windows is working.
Please follow the steps in this
post to see if Windows can detect and repair any damage in its core files.
Once those are done, I think you should open an older project (if available) where you were accessing your media clips from their original locations. PD can't be confused since it only knows about the specific clips you've imported into each project, but it sounds like a nightmare for you to try and keep track of which files are where.
Generally speaking, it's better if your media clips are on a separate drive (and you have tons of free space on your D: and F: drives). There's no harm if they're on the C: drive, althugh PD would probably be able to access them a little bit faster if they're on another drive.