Unfortunately this is a known issue. When you undo/redo changes in the workflow application, the amount of memory that the ppwfg.exe process uses increases. If the workflow application is never closed, this amount will continue to increase until it reaches a threshhold of around 1.5Gb, at which point it will corrupt your active config file. This is most likely what caused the error message.
To try and resolve this:
Make sure your Undo/Redo option is turned ON (in case you turned it off earlier)
Delete one of your processes. Pick the smallest possible one that you know you can recreate easily if anything goes wrong.
Try saving the config and check whether the file was saved properly
Before doing anything else, try Undo’ing the last action (when you deleted your process) to see if the application is able to recover it.
If the Undo method worked, it means you should be able to perform the above procedure several times until the save operation is successful. You may end up losing a few processes but it’s better than losing everything.
Note: If you have autosave enable in preferences, it’s possible you’ll have a config file with the extension “._as” in your PlanetPress Watch folder. If you have that file, you can change the extension to “.ol-workflow” and then load that configuration.