cookie bug

Hi, I might facing a cookie bug problem in PHP4. I set the cookie with the following syntax. setcookie("useruser","$values",time()+10800,".domain.com",0); the $values of the cookie is acquired from the login page. I have tried to login from two browsers at the same machine. The first browser, I login as mark. so the cookie value is mark. The second browser, I login as Eric, so the cookie value is eric. Now I am trying to retrive the values of the cookie from the two browser, and one of the browser 's cookie value is being changed. I mean the two browser at the same machine having the same values....like mark....or like Eric. I wonder is this a bug.?? if no, what did i do wrong.?? On the other hand, If I set the cookie with "setcooke("useruser","$values"); Then, It works perfectly, no replacement occured. Can anyone tell me what is happening. Thank you Mark Lo