Platform
Win32

JDK Build
Mantis b18
java version "1.4.2-beta"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.2-beta-b18)
Java HotSpot(TM) Client VM (build 1.4.2-beta-b18, mixed mode)

Descriptions:
For the available diskspace,
        1. windows report 166M,
2. mantis b18 installshield only report 90M
  3. hopper fcs installshield report 131 M

How to reproduce
1. Java installshield will report the number of available diskspace only when it complain lack of diskspace
2. So, in order to reproduce this bug, you need to make sure your available diskspace less than 378M which is required by mantis b18