Lightroom catalog corrupted and now LR won't open

My Lightroom program has a big problem. I'm running up to date CC on Windows 10. It started by LR crashing when I was exporting images. Then it would not open at all. I imported a  catalog backup and it too became corrupted. This has actually happened to me before, a couple of years ago. So I tried what worked then. I parked a fresh catalog backup alongside the folder with the corupted catalogs and the image files. It opened normally and from what I can see is fully functional. This was my experience two years ago as well. But in this case something in the original folder is corrupting any new catalogs and is keeping Windows from copying it. I cannot make fresh backups. I also cannot open Lightroom on this computer now with any of my catalogs. 

My conclusion was that the problem is upstream of the catalogs. If I was on my own I would delete and reinstall Lightroom. But I thought I should put the problem before the forum before I do too much & can't remember what I did. Besides, the problem does seem to be inside that one catalog folder. There have been other problems with this installation. I have both Photoshop CC and Beta on this computer and they  don't get along that well with LR. But that is an old problem. If I do reinstall Lightroom I will reinstall Photoshop as well, without Beta. I hope I have made this clear.

Thanks in advance to all.