Adobe Distiller is an app that can convert (i.e. distill) PostScript files into PDF files while running in the background. It has been reported that Distiller will stop working on Macs running Mavericks if the app is hidden.
The confirmed workaround for this problem is to disable App Nap. To do this, do a File->Get Info on the Adobe Distiller app, then check the option for “Prevent App Nap”.