Hello Bellawood,
This Java script Error problem, if you installed CS3, AI, PS or ID or any application already have in system or you uninstalled it, and installing again... this Java Script Error message will come.
This guide line is for Mac OS X only not for tested on Window system.
There are 2 ways to install again CS3.
1: format your system and install CS3 or remove all adobe folder your your system and install.
2: If you already installed any CS3 application and installing any other and you are getting Java Script Error message... do this, in hard disk/library/application support/adobe/... remove caps and backup folders from there and keep in safe place and install your application... hope it will install. after installing run that application... and it will run, and if you will try to run already installed application.... it will not... because you removed that application backup and caps file from adobe folder. Keep backup and caps folder in safe place and replace backup and caps folders with earlier folder which you saved in safe place. and repeat this process.
I know this is little tricky... and complicated. Better is remove all adobe files and folders from your system and install CS3 again.
regards.