We are working on Oracle 7.3.4 with SCO-Unix.
FOr the past 3-4 days, we are infilcted with severe listener problem. Listener is always hanging in the middle of session.On reading the listener.log, it gives following error.

TNS-12535: TNSperation timed out
TNS-12560: TNSrotocol adapter error
TNS-00505: Operation timed out
SCO System V/386 Error: 90: Operation would block

Then we have to kill the listener process from OS and again restart it.we shutdown the database every evening but not listener.

Please tell us the solution.