Hi Jose,
There is nothing to do with DIR_LIBRARY environment variable.
This is because of your client version compatibility with current OS patch set. Just compare the oslevel and it's ML/TL level with the system where it is working fine.
It looks like, pre-requsites related to OS patch set were ignored while perorming oracle upgrade.
solution is to change the path of oracle client and point it to earlier oracle client version till you get your OS patch upgraded to the recommended patch level.This is tested workaround.
Do let me know if you still face same problem after changing client path ..
Cheers !!!
Ashish