two-task common
errors are generally RDBMS related issues, but could be caused by a problem with SQL*Net, or an application (i.e. Pro*C).
ORA-03106 可能的原因：
======== 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.
Well, One way to resolve this is to
Try synching the NLS_LANG variable on the client and server.
ORA-03106: fatal two-task communication protocol error
原文：http://blog.csdn.net/lixora/article/details/18796975