On CISCO switch u can use this command to automatically disable a port which cause a loop in your network :

errdisable detect cause loopback

You have to analyse Syslog messages to see if a port get disabled.

If a port get errdisabled, you will see its status using the "sh interfaces status err-disabled" command.

Concerning HP switches, procurve generally generate logs concerning loops or "broadcast storms", again, you will have to check the logs.

In all cases, activating the errdisable function on your cisco device should let you find from where the problem is comming.

For instance if you have a switch A (cisco) and a switch B (hp), after activating err disabling function on switch A, if you create a loop on switch B, the trunk port between A and B will come into err-disable state quickly so you will be able to locate where the problem is coming from.

One last thing, remember if you are in a production environment that you could isolate some parts of your network by enabling this function. So be careful about using it.

P.S : you could also use thoses commands so, when a port goes err-disabled, it will enable again automatically after a 30 seconds period :

errdisable recovery cause loopback

errdisable recovery interval 30