Executing process in background

Hi, I have to start a task on the server side that is going to take pretty long to process in the server side. So I would like to show a message to the user and ask him/her to check again later. But starting a new task holds up the thread and won't let me exit the php. The user's browser does keeps showing busy. I tried to create a new thread using pcntl_fork, but my php doesn't allow that as it has not been compiled with pcntl support and its not possible to change that. I also tried to create a script that would do the task and called the script using system command and passed an '&' at the end to make it process in background, but that also keeps the main thread busy. Any solutions? Thanks -Surya