I remember those floppies... The 8th disk was kinda finicky on older hardware. I think that's where the installer actually tried to switch from DOS to Windows mode. If it failed for whatever reason, you had to start again from the 1st disk.
But you could be a little more scientific and try different parameters once you went back to disk 1. Maybe also remove some of the more questionable drivers or memory-saving tweaks from your DOS configuration while you were at it. Or perhaps it was just a flaky floppy drive that randomly flipped a bit somewhere.