We faced the same problem when we migrated from Oracle8i 8.1.7 to Oracle9i 9.2.0.1 using export import. Don't know why it happened? But since we were migrationing across machines having same OS i.e. AIX 4.3.3 we used the manual migration approach of using ftp for copying the datafiles and then recreating the control files and running the upgrade scripts.

I still don't remember why we didn't raise a TAR for it.