No idea why but to minimise work loss goto file, preferenses and click on autosave button. set the autosave to 1 minute so you dont loose to much work. Could be that your machine runs out of memory.No idea why but to minimise work loss goto file, preferenses and click on autosave button. set the autosave to 1 minute so you dont loose to much work. Could be that your machine runs out of memory.