Hi Rowena,
I am Rajashree, I can certainly check the validity & activation count of the CS3 serial number. Unfortunately under the Adobe ID with which you are logged in has only LR6 standalone version serial number, please share the CS3 serial number by personal message, I shall also check if other Adobe support engineers can throw some light in this.
Regards
Rajashree
Moving this discussion to the Downloading, Installing, Setting Up forum. My thanks to everyone who has attempted to assist Rowenac in this discussion. Please feel free to move or refer future discussions of this type to the Downloading, Installing, Setting Up forum. Our community regularly answers download and installation questions for Creative Suite and other perpetual software titles.
Rowenac you mentioned that you were being prompted to insert additional discs during the installation process. If you have a retail installation license then you can download a fresh copy of the installation files at Download Adobe Creative Suite 3 products .
If you continue to receive installation errors then can you post any specific errors you discover to this discussion. The installation errors will be contained within the installation log files. For details on how to locate and interpret the installation log files see Troubleshoot installation with install logs | Adobe Creative Suite 3, Adobe Creative Suite 4.