If sometimes the weblogic server hangs without leaving any clue behind for debugging just try this out and it might solve the problem.

rename the ldap directory inside

“<Domain_home>\servers\<server_name>\data” 

and you are saved for the day..

one clue for doing the above change is to check for the log and if you see this line then the workaround will solve your problem

“<IIOP>”

usually after enabling iiop the server will start with the security. So the corrupted ldap causes the problem of server getting hanged.