Please
update your profile.
Also, give us further information :
1. How much RAM on your server?
2. Did you remove & deactivate SELinux?
3. 32 bits binary for RHEL 5 (that you used for CentOS 5.5) was deprecated. Why don't you pick 64 bits based on RHEL 6/CentOS 6? is this for testing purpose only or also for production use?