1. In Internet Explorer, click Tools, and then click Internet Options.
2. On the Security tab, click Local intranet, and then click Sites.
3. Click Advanced, and then type: *.domain.com or an IP address range (for example, 157.54.100-200.*) in the Add this Web site to the zone box, where domain.com is your company and top-level domain names.
4. Click Add, click OK, click OK, and then click OK again to close the Internet Options dialog box.
5. Restart the computer.

Details: http://support.microsoft.com/kb/303650/en-us?spid=2073&sid=global