There was a situation when the system was set to run across every personnel number through the whole system. With thousands of employees, it took to much time so system hung out. Why? The user has turned on Object Manager in PA30 to show all employees according to permissions. The system opens transactions, sees object manager and starts loading employees. And hangs out of memory. No way to open transaction as it opens object manager every time. Solution?
Disable Object manager or temporary hide it. In user parameters (transaction SU01, SU3) you can insert these params to hide or disable last search results.
It will reset current settings for the user.