Yipee! I can't believe how slow thinking I am. but I'm very happy to share my stupidity, as I suspect I'm not rare. Anyway – these pages – it didn't really have anything to do with the rastorization – except that it wasn't working well, and I decided to get rid of it. And in getting rid of it, I simply dumped the pages these images were filling. See how stupid? When you toss pages without dealing with the content first, you get overset text. I didn't notice it, because there's a place in my front matter than always registers as an error – even though the text is all visible. But after starting fresh files and copying pages one at a time, and then exporting to see if I was getting the error still, I actually began to SEE the overlaid text. Five hours of suffering, and I finally saw the double text. And then chased down the overlaid text error. I had to insert new pages and dump the text on them (at one point, I had done that, over and over, and every time I had shift clicked to dump the overlaid text, I got empty text boxes – it was very confusing).
At this point, I was finally smart enough not to dump the pages, and not to delete the text boxes either – which does not solve the problem. I had to go in with the text tool and deal with the text, selecting and deleting – I had a problem with a page break character that would not go – then the frame still wanted me to believe there was overlaid text – even after it was all gone. So I went through the process again, and this time, deleted the empty text frame. And FINALLY – FREEDOM!! It felt fabulous – ten hours of slogging ignorantly around, but I finally solved it myself. And maybe someone else out there will find themselves with the same mess. Maybe this will help.