This error comes when you are using Winlnet option from runtime setting for web_set_user request.
Reason is when using winlnet option then HttpSendRequest time out only occurred when any transaction takes more than 30 sec to connect to server. This default 30 sec time is because of the use of WinInet Replay engine. Thus this error pops up when you are running script with winInet replay and transactions are taking more than 30 sec. Only thing to get rid of this error is to fine tune the whole system and check the backend and servers to see any request.
And the other option is to use web_set_max_retries ("X") to increase the limit of 30 sec, where X is no of time you want to re try and send request to server but problem is if server don’t respond within 30 sec then you will again get this error.
I suggest you to check the behavior of application in peak load and verify if response is taking more than 30 sec and discuss this issue with application stake holder.
Thanks,
Deepak