I edited some dvdrs using Ulead Movie Factory 2, and burned them using the Sony DRU 500A. With 3 video files or less, they play fine on the PS2, over 3 and the PS2 says "unable to read disc. It will go to the 4th and 5th videos menus, but when you select a chapter, you get an error message. The same disc will play completely in my regular Sony standalone dvd player (3630). I used no compression, the required disc space was less than 4 GB. What's wrong?

Thanks.