Ah okay, 20.000 files is a lot. I can imagine that this doesn't work. I will add a more graceful solution for such huge files. I don't know why the 500 kB file doesn't work, but of course, the same applies here. If the file contained 20.000 very small files, it would lead to the same problem. If you like, send me the file by mail, and I'll have a look.