If you are for some reason moving your database from 32-bit to 64-bit server, a simple copy-paste is not enough. PL/SQL packages are compiled with one word size on 32-bit server and need to be recompiled on 64-bit or the following error might appear: ORA-06553: PLS-801: INTERNAL ERROR [56319].
Metalink note 62290.1 describes in detail what you have to do. Worth to mention is that if you are moving and upgrading your database to a newer version, the conversion is not necessary because it is done automatically (with the exception of 10.1 to 10.2 upgrade).
There is also a problem on 64bit Linux that causes the utlrp.sql script to disconnect and in the alert log these errors can be seen: ORA-07445: exception encountered: core dump [_intel_fast_memcpy.A()+10] [SIGSEGV] [Address not mapped to object]. To avoid this, OLAP option needs to be removed and added again before running utlrp.sql (as described in another metalink note: 352306.1).