I am getting some strage errors intermittedly.

My Oracle instance is running and after some time it is not accepting new connections ( Sessions ). I can continue work on existing sessions. The error messages I am getting are

TNS-12500: TNS:listener failed to start a dedicated server process
TNS-12560: TNS:protocol adapter error
TNS-00530: Protocol adapter error

This is from client end. Then I tried to connect svrmgr at server end that time I am getting ORA-12203 TNS Unable to connect destination.

Can any one help to solve this problem.

I contacted Oracle Suppoprt and they advised me to install patch 8.0.2.6. Still I am getting same errors after installation of patch.


Software details

OS: WIN NT4.0
Oracle Version : 8.0.5.0.0