Thanks a lot your advice helped me locate the same problem.using show platform cpu packet buffered i saw a lot of packets coming from certain ip adresses linking to a ESXI Server which had Teaming enabled and our side on the switch didnt had Ethercha...

Thanks tcroziercisco,It makes perfect sense for a Cisco ACS to stop and start its the only thing i do for every problem i get.I'll be glad when we are going to use something else because this product is only trouble since we got it.