Publishing is stopped while still appearing to be busy.

In the event log details following error is shown:

An unexpected system failure occurred: There is not enough space on the disk


 

Make space on the appropriate disk.  The host name can be found in the event details.

Probably publish temp folder is too big: 
InfoShare\Data\Publish\Data
For older releases beforeTridion Docs 14 check:

InfoShare\Data\PublishingService\Data\DataExports

You can delete older data in these folders or anything not currently publishing.

and to have it auto removed when successful be sure the cleanup box is checked.

the cleanup can be set in the output format-->properties
  The cleanup box can be checked:
 

Disk is full because the clean up hasn't been set.