Error: Unique constraint on dtree, LAPI add object, 101107

Environment: Livelink 9.7.1, .NET 3.5, Oracle 10, ADN module, heavy category/attributes
Problem: Multithreaded LAPI app loads several documents into Livelink and creates new folder structures, permissions, RM Classifications, and categories. Once in a while, we run into this error on the Livelink server side: Oracle error: (1) --> ORA-00001: unique constraint (LINK_OWNER.ADNIDS_INDEX1) violated

The LAPI error is CreateObjectEx Failed. Message=Error adding categories to node errMsg=Error saving generated number. Status=101107 (Fault Detail is equal to An ExceptionDetail, likely created by IncludeExceptionDetailInFaults=true, whose value is:
LapiException: CreateObjectEx Failed. Message=Error adding categories to node errMsg=Error saving generated number. Status=101107

Theories:

• ADN is blowing up again. 
• The LAPI port is getting overloaded.
• LAPI sucks.
• The database is being overwhelmed by multiple transactions from multiple users (adding one object to Livelink is usually about 100-200 various transactions, so do the math if there are 100+ users).