Having problems with generating CSV files

Hi all. I am managing a field study under way now and I am having problems with generating CSV files. I run ODK aggregate Version 1.7.4. I had no problems with downloading until yesterday and we are download about 500 fairly long questionnaires with one optional photo and one audio file (maybe 100 total). I use a Chromebook so I cannot download ODK Briefcase as an option. I have my AppEngine on unlimited billing. Can't put my finger on the problem or find a solution. I have also vacated my browser to free up ram. I have looked at others who were facing similar problems in here but could not really understand some of the programming fixes. So I am turning to you now. If all fails, I will download everything manually, but hoping you can help. My name is Karana and I am in Côte d'Ivoire