I administer an ECC system running on ERP 6.0 EHP6, with separate instances for database, central instance and 1 dialog instance. Today all the 3 instances got 'hanged' such that users were not able to log into the gui. I tried killing PIDs from OS but still was not able to access the systems. I had to stop all instances, reboot the servers and start again. Now I want to determine the cause of the issue. Please tell me where to start looking at - the work directory? I am suspecting some user activity to have caused this....