Case 1. Fails after adding user to a domain.
When opening a file, or creating a new file, the system saves the files to the local drive. Normally, that is in a folder called RushFiles. The files are encrypted with the local user certificate, so not even an Admin can open the files.
If the user / PC is then added to a domain, then the certificate changes, and the client needs to be reinstalled. This is because the local folder with the local files becomes inaccessible.
This is a security feature to protect the documents from all other users, including the admin.
Case 2. Fails after installing as an admin, and then using the same RushFiles login on another user on the same PC
The problem is the same as in case 1. The folder is first encrypted with the admin / user on the first RushFiles login. Then, when the user is switched, but the same RushFiles login is used, the new user will be prohibited to access the folder where the files are stored locally.
Fix for case 1 and 2.
1. Start File Explorer and enable it to show "Hidden Items" under the "View" tab.
2. Search on your local drive(s) (C: D: or the like) for a folder called "RushFiles".
3. In the "RushFiles" folder, find a folder with the email of the user that is being used as login.
4. Exit the RushFiles PC client.
5. Delete the folder with the user in question.
6. Start the client again. The folder will now be recreated with the correct credentials.