Windows 10 - Dropbox stopped working a few days ago; won't reinstall - errors in DBGCORE.DLL

I've fixed the problem :sunglasses:

It appears that the copy of DBGCORE.DLL was damaged in the Windows 'Image' (a part of windows where backups of critical files are kept); Windows wouldn't allow the use of the DLL, and couldn't repair it. I used the following method to fix this:

1. Use the Microsoft Windows Media Creation Tool to download a fresh copy of Windows 10 ISO file
2. Mount the ISO file (right click on it in Windows Explorer) - it will then appear as if it were a CD inserted into your computer.
3. Using Windows Explorer find the file ..\sources\install.esd within the ISO, and copy it out to C:\install.esd (this file contains an image of all the files in Windows)
   
4. Open a Windows Command Prompt as Administrator, navigate to C:\ and issue the following command:
   
   dism /Get-WimInfo /WimFile:install.esd
   
   This will tell you which versions of Windows exist in the ESD file, and the index to access each one (I am using Windows Pro, index 6)
   
5. Then extract that version of Windows from the ESD file to create a new Windows Image for your version of Windows only, containing the current versions of all files, again using DISM (replace '6' with the index number for your version of windows, determined above). Type the following, without any carriage returns (it will wrap to a second line in the command prompt)
   
   dism /export-image /SourceImageFile:install.esd /SourceIndex:6 /DestinationImageFile:install.wim /Compress:max /CheckIntegrity
   
6. The file C:\install.wim file will now contain a single image, for your version of Windows (with index 1). You can use it to repair the image 'embededed' in your windows install using the following command:
   DISM /online /cleanup-image /restorehealth /source:WIM:c:\install.wim:1 /LimitAccess
   
7. You then need to use the repaired Windows image to repair the installation - you do this as follows:
   SFC /SCANNOW
   
8. You can check What repairs were done by looking in the file C:\Windows\Logs\CBS\CBS.log. Also, if you had run this command first, it would have told you that the files were corrupt, and couldn't be repaired.
   
9. Then install DropBox!

Thanks to everyone who tried to help here - I found the details of how to do the above repair by searching elsewhere on the web, but special thanks to www.wintips.org where I discovered how to create my own WIM file (which is critical if your windows installation is corrupted). I think the problem was originally somehow caused by a windows update that went wrong...hopefully this may help someone else

-Steve