Have you checked Metalink? One of the documents in metalink states the following :

Possible reasons for the ORA-03106 errors include:

1. Incompatibilities between the client application and the RDBMS server. For example, version incompatibilities, or a client trying to use a
feature not supported by the database kernel.

2. When using database links or gateways.

3. Network or SQL*Net problems.

4. Corruptions.

5. PL/SQL - language related.


There are many more documents in metalink on this error.

Thanks