Redirect Browser one time only using Javascript

Hi All

Is anyone familiar with Joomla CMS website.

I had tested my cookie script on a regular HTML web page and it worked fine.

When I try to put it on my Joomla 1.5 website, I cannot get the cookie script to work.
It generates the alert message if IE is detected, but it shows it on every page visited which means that the cookie for some reason is not being set and so constant alert message.

Thanks