One of the changes Internet explorer 7.0 will see is a tightening of restrictions on the zone settings. Currently, there are four security zones for web sites: Internet, Intranet, Trusted Sites and Restricted Sites. Explorer tries to autodetect if a site is within the intranet (which becomes more trusted), or the internet (which becomes less trusted. The problem is this detection can be tricked and so, malicious websites can run in a less restrictive zone.