Crap! Do you know this message? Most probably your console just crashed a minute ago while you were editing this application and you’re trying to open up this application again. Well, too bad, please wait for 30 minutes and then come back please.
This is because your lock on that object has not been released the moment your console crashed.
For more information on this, use the search engine of your choice (google *g*) and look for SEDO (Serialized Editing of Distributed Objects)