If you are trying to download Payback and receive a message saying "The set up files are corrupted, please obtain a new copy of the program." or similar, it means the downloaded file is not complete, The following steps will fix this issue;
First, please ensure you make a backup before upgrading Payback, (Admin / Backup).
Next, clear your Internet Explorer cache;
To clear your cache:
1.On the Internet Explorer 6 Tools menu, click Internet Options. The Internet Options box should open to the General tab.
2.On the General tab, in the Temporary Internet Files section, click the Delete Files button. This will delete all the files that are currently stored in your cache.
Now exit from Payback and click on the following link, and when prompted, SAVE the setup.exe file to your desktop;
http://www.payback.ie/downloads/setup.exeWait for the download to complete, the file is about 8.5Mb.
When the download is complete, go to your desktop and double-click the setup.exe icon to start the installation. Follow the steps.