Whenever i run wpi.hta, down the installation queue, i find the following error message : Windows Post-Installation Wizard Javascript Error report Message:'undefined' is null or not an object url:file://k:\softbox\wpi.hta file:generate.js line:241 i use version 3.5.1 currently , but seeing this message right from version 3.3. to provide some detail about my problem, here are few observations: 1. i run softwares from config.js script, then some cmd files like cleanup.cmd etc. but my config.js is not running completely. after, say, appPerInstallWindow=25, cleanup.cmd runs before all appWindow gets completed,thereby, rebooting my computer. 2. although it shows me error in line 241 in generate.js , but syntax of line 241 remains same in version 3.3 and 3.5.1 please help.