When my user tries to run a map I am getting the error message “[ODBC Excel Driver] General error Unable to open registry key Temporary (volatile) Ace DSN for process”

This is caused by the user not having the proper rights to read the folder location of the source file. Move the source file to a location where the user can access it and update the map to point to this new file location or provide the user read access to the folder where the file is currently located.

If it looks like the user does have access to the folder, I would recommend removing that access and setting it up again.