Timeout error on Process start

Hi,

we're using Netweaver 7.3 and we made a new BPM process.

Our problem is that when we call the webservice to start a new process instance, the instance is correctly created but the webservice "hangs" (i.e. does not give a response) until the timeout is reached (e.g. 60 seconds).

Can someone help me to troubleshoot that? What could I check to understand the cause of the problem?

Thank you,

Pietro