I've gradually cut down the size of a 70 page document until I got it to import at 2 pages. Have had this problem with other documents in this project but not to this extent. Usually just had to split into two files. After several attempts, it is not unusual for RH to crash.
The files have had all page numbers removed from cross-references.
There are no unresolved cross-references.
Framemaker 7 (also tried a Frame 9 doc)
I believe I found the problem. I sometimes "stack" Framemaker tables, meaning their markers run together and aren't separated in any way. I was able to perform the RH import after I "unstacked" these tables.