reset sandbox -- whirling circle never stops

I am running CFW latest stable version, on Windows 10 pro x64.
When I try to reset sandbox, it deletes most of the contents, but gets stuck, I see a never-ending whirling circle.
1 how to fix this problem?
2 as a workaround, is it safe to manually delete the contents of VTRoot?

Upon inspecting the sandbox contents, I found a few files from Adobe that were undeletable, until I took ownership of them. I assume that those files were causing the issue.