I've burned some more discs with ImgBurn and found that each time I burn a data DVD with UDF, I will get a 0-byte file showing only. Ejecting the DVD and reinserting it still shows only a 0-byte file. However, once I eject the DVD, insert a different DVD, then replace it with the original one, the file I tried to burn then shows up with its proper file size and I'm able to open it.
I'm not sure if this is ImgBurn's problem, Vista's, or just my computer but I thought I would post this anyway.
Thanks again to the developers.