Alternatives to Flush()

I have a particular PHP web page that can take over an hour to process. When visitors come to this page, I want the code to redirect them to a separate page at my site. After the redirection, I want the PHP script to continue operating on its own until the process is complete. I am attempting to implement this is by sending a "Location" header to the client. This header is sent out near the top of the script. After sending the header, I call Flush(), then the script continues into the heavy lifting. Finally, the script quietly terminates with an exit call. Neither the flush() or ob_flush() calls are working (I even tried calling them both). Regardless of what I do, the server will not send the "Location" header until the script has completely terminated. It appears that my hosting provider has Flush() disabled. I have thought about using Chron to accomplish this. However, the smallest Chron resolution is minutes. This could cause the visitor to wait for up to a minute before Chron wakes up and starts working on the process. There has got to be a better way. Does anybody have any recommendations? Thanks, Ron