I've resolved the problem after looking at other posts about these errors. No one gave a definitive solution, but I got some ideas on where to look.
The problem appears to be with the security permissions on the C:\Windows\Installer directory. This is a hidden system folder, so you may have to change your Windows Explorer view options to be able to see it (Organize > Folder and search options > View tab).
For some reason the permissions had been altered and that caused a problem when an attempt was made to install or uninstall any software. I checked another Windows 7 machine and amended the permissions on the problem PC accordingly. The permissions required on the folder are as follows:
- SYSTEM - Full Control
- Administrators - Full Control
- Everyone - Read and Execute
Yes, he was having some problem with his previous install
Hence Reader X installation was unable to uninstall previous version and was failing.
Change Permissions :