Iptable initscript hangs while loading 'xt_state' module in RHEL 5.

Issue

• Why does Service iptable start hangs while unloading iptable module in RHEL 5.

# service iptables start
Flushing firewall rules:                                   [  OK  ]
Setting chains to policy ACCEPT: filter                    [  OK  ]
Unloading iptables modules: 

• When trying to unload the module the following errors are observed

-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= 
Apr 8 12:08:05 hostname modprobe: FATAL: Error inserting xt_state (/lib/modules/2.6.18-402.el5xen/kernel/net/netfilter/xt_state.ko): Unknown symbol in module, or unknown parameter (see dmesg) 
Apr 8 12:08:05 hostname kernel: xt_state: Unknown symbol need_conntrack 
Apr 8 12:08:05 hostname kernel: xt_state: Unknown symbol ip_conntrack_untracked 
Apr 8 12:08:06 hostname kernel: Removing netfilter NETLINK layer. -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=