2007/11/09! 03.56.29! E00549! Enq_pty! Tty.c! 119! PID (22597)! Operations ioctl (TCS

helo,
i got accessing system from putty.

a user has had System Telnet up (for hours at a time) and been running various commands from the CUI menu.(its just client application) The following message appears over and over again in the account log:
2007/11/09! 03.56.29! E00549! Enq_pty! Tty.c! 119! PID (22597)! Operations ioctl (TCSETAW) failed,
file 'tty - errno 5: Input / output error

This problem is still happening. While the problem can be resolved, at least temporarily, by restarting all services.but I need to find out why this is occurring. The results vary slightly, but basically the client applications become unable to connect to the system.

what to do
Regards,
Amit