Must use Java Script.

Internet Explorer 6
On the Tools menu, click Internet Options.
Click the Security tab.
Click Custom Level.
Scroll to Scripting. Under Active scripting, click Enable.
Click OK twice.

Netscape 6
On the Edit menu, click Preferences.
Click Advanced.
Select the Enable JavaScript for Navigator check box.
Click OK.

Opera 7
Open Opera.
Select Quick Preferences from the File menu.
Make sure Enable Javascript is checked.
Click Reload.