What "tool" are you referring to? What do you mean by "logs off"? Do you mean that within a ColdFusion application, user's sessions are being closed?
You'll have to provide a lot more detail about exactly what is happening before anyone can assist you.
coldfusion 10 users logs off automatically from the tool after first activity everyday when they log in
I have understood this as, when users log in everyday, after the first activity, coldfusion logs them off automatically from the tool. If that is so, then it could mean that sessions are not maintained between requests. You will then have to configure your Application.cfc of Application.cfm file to instruct ColdFusion to maintain sessions.
You are right within a ColdFusion application, user's sessions are being closed when we submit any request and redirect to the login page first time when we login everyday. And then after we login again the application works fine.