I'm having a similar problem with ID4. Have prepared the INDB document, checked the TOC, run preflight successfully, and then export for digital editions. Consistently causes ID4 to stop working. EPUB seems to be created, however.
Recently, there has been a problem; the EPUB for a particular book doesn't include the TOC no matter what I do or how I reformat.
Running Vista with ID4.
Would very much appreciate any help.
Five Rivers Publishing