Problem importing IFO files and burning MPEG's

[dean5150]

I used a program called DVD Shrink to rip a few different DVD's. I'm taking bits and pieces from each DVD and compiling one DVD. Movie Factory will only let me import IFO files from certain DVD's. My thinking is they should all be the same, but obviously they are not. Anyway, the files that I do import into Movie factory, which are converted to MPEG, seem to have different attributes and will not burn to a disk.
1. Why can't I import certain IFO files?
2. How do I get my DVD burner to accept the MPEG's once they have been converted from IFO?
Thanks for your response!