The frequency of the following error is occurring more and more:
ERROR: 0X80070780 File cannot be opened by the system
Trying to open several PDFs and it says it is impossible to do. It feels like the I am working off a corrupted hard drive. This strikes at the heart and soul of using Dropbox as it quickly leads to the conclusion that Dropbox "Cannot Be Trusted".
Cannot see anything I am doing wrong. Help would be "Much, Much Apreciated"
I agree with you, that many new "features" of Dropbox look like bugs. According your description, seems you are disturbing by a bug with name "Smart Sync". Very poorly implemented and as a result such issues come up. If you can, turn this feature (bug) off. If you need to save disk space, considered "Selective Sync". As a last resort (you can't live without "Smart Sync") make sure the files you are working on are set 'local' in advance. 🤷 That's all you can do with Dropbox right now.
The problem is related to credentials. Dropbox app in Windows uses onedrive to create a virtual drive. You want to be sure that you are logged into onedrive with credentials that grant you access to the windows local drives or Adobe apps you expect to use.
Best to uninstall and reinstall the dropbox app, and it should reset credentials. Worked for me.