phpNuke Problems

I’ve just installed a copy of phpNuke on a domain that is accessed from multiple machines behind a NAT firewall. My problem is that when we have multiple users logged on and someone hits the home link they will get another users home page, refreshing the site will fix this but it appears to be some sort of server side caching as a page refresh will correct this and reload the correct page. Has anyone got any clue how to stop this happening?

Thanks in advance for any advice anyone can give me