Are you logged on as an administrator? The Workflow service expects to be able to write the config to the C:\ProgramData\Objectif Lune\PlanetPress Workflow 8\PlanetPress Watch folder. Check if you have writing rights to that folder.
Also, make sure there’s no undefined task in any of your processes. This sometimes happens when you delete an Output task you’d added before but don’t replace it with a vaild alternative.
Well that explains that: if you can’t even see the Programdata folder, it means you probably don’t have the rights to send files to it or to one of its subfolders. Ask your IT department how to change that.