Hi,
try to reduce the scope of your test/troubleshooting.
E.g.:
* use wireshark on your laptop, next ping from 1 host to some other host. Do you see the ping ?
This will tell you if all packets are flooded or just some packets.
Verify these mac-addresses with "dis mac-address" on the switch.
* For the packets which you do see in the wireshard, take the destination address and lookup on the switch with "dis mac-address".
* Check these mac-addresses on your PC arp table (arp -a), you may need to perform a ping to the host IP first.
* do you find any missing matches between switch mac-tables and local pc arp tables ?
Do you have microsoft NLB clusters in the network ? The will use a multicast or unknown unicast mac-addrses for their ARP reply, which forces the switch to flood traffic.
Good luck,
Best regards,Peter.