Sorry about missing your signature
It sounds like you may have corrupt files, especially if the process that you carried out was the same for both files but not the other.
I once had a problem with a file that absolutely refused to budge from the colour magenta. This too must have come corrupted somewhere along the line. Fortunately it wasn't too much of a problem- as the file opened up in Corel draw, to then be used in a laser cutter- but it was still magenta!!
You may have to re-draw if it's a problem.