What version of ID? Have you updated tot he latest patch for that version? I think I remember some bug that caused pages to go blank related to keep options, hyphantion of the last word in a column, or span/split columns in CS6, but I'm afraid I don't recall the details. Do you see any indication of overset text? Is the text there in Story Editor? Does closing and reopening the file bring it back?
Thank you Peter! I am using CS6 so I will download latest patches. I did have overset text on one page. I wonder if correcting it caused the blank pages? I will try your suggestions next time it happens. Thank you for your response. At least I don't feel like I am the one going crazy.