To Restart a Tiled Rendering After an Interruption

Select Drawing > Utilities > Image > Save Image .
The Save Image dialog opens.
In the Tiled Rendering section, click the Continue button.
The Continue Tiled Rendering dialog opens.
In the file type list box, select the control (.bkt) file.
Click Open.
The Continue Tiled Rendering dialog closes and focus returns to the Save Image dialog.
Click Save.
The rendering process resumes starting with the next unfinished tile.