The Browse Server option in the ColdFusion Administrator is actually a Java applet that requires a Java Runtime Engine (JRE) to be installed and configured for use with your Web browser. An error may occur on Windows 2003, the original version of Windows XP, or Windows XP SP1a, which do not have a Java Virtual Machine installed by default. The article below contains a fuller explanation of the problem and a workaround.
ColdFusion MX: Unable to Run Java Applets in ColdFusion Administrator