I tried to install Netbeans 6 Beta 2 on Linux (Ubuntu 7.10 gutsy) and get the following error:
$ Configuring the installer...
$ Searching for JVM on the system...
$ Extracting installation data...
$ Running the installer wizard...
$ /usr/share/themes/Clearlooks/gtk-2.0/gtkrc:42: error: lexical error or unexpected token, expected valid token
The installer stops with a blank/grey dialog after this error.
After changing the theme to Human:
$ /usr/share/themes/Human/gtk-2.0/gtkrc:71: Engine "ubuntulooks" is unsupported, ignoring
$ /usr/share/themes/Human/gtk-2.0/gtkrc:242: Priority specification is unsupported, ignoring
$ java -version
java version "1.6.0_03"
Java(TM) SE Runtime Environment (build 1.6.0_03-b05)
Java HotSpot(TM) Server VM (build 1.6.0_03-b05, mixed mode)
Symptoms are very similir to descriped in the Issue 117172.
Most probalby it is the Swing bug.
Try the workaround (export AWT_TOOLKIT=MToolkit) and reopen the issue if it doesn`t work for you.
*** This issue has been marked as a duplicate of 117172 ***