cookies time?

Well, reading the documentation about cookies i saw that the function time() works using UNIX epochs. If I try to use this function (or mktime) in windows, the php shows a white page, like there's an error somewhere. It's a problem with windows machine's or there's another solution to this? Meanwhile, I put no time option (so cookie expires at the end of the session) but i would like to try to set up a timeout. I don't demand absolute solutions, I only want a clue to work on. Thank you :)