This problem is addressed in ArcGIS 8.1 Service Pack 1. See Related Information section to download this pack.
When joining table-A to table-B to form table-B_table-A, and then joining the latter to layer-C, ArcMap either crashes or displays incorrect values in the join fields.
ArcMap crashes when the table-B_table-A join is a cross-database join, such as joining dBASE file and an INFO table, or both are dBASE files, but come from different directories.
If the table-B_table-A join is not a cross database, ArcMap will not crash but incorrect values may appear in the joined fields. For example, when you open the table window, you may see blank or repeated values in the joined fields.