I found the source of the following Expert log entrys i've got:
2013.07.18 09:58:28 ZorroMT4 EURUSD.G,H1: function 'MT4Respond' call from dll 'ZorroMT4.dll' critical error c0000005 at 10001992.
This error shows up when i let Zorro run and accidently closed the Zorro EA and restarted it.
When i stop Zorro and reload the Zorro EA into an asset and then start Zorro again the error has gone...
Just for your info.