Is it possible you downloaded the 64 bit updates when you have 32 bit Photoshop or vice versa?
You could go here and download CS5 again, just in case there is something slightly damaged in your existing installer.
https://helpx.adobe.com/creative-suite/kb/cs5-product-downloads.html
Possibly it might be an idea to uninstall what you have then run the Adobe cleanup tool and reapply the freshly downloaded version of CS5 then with fingers crossed see if you can run the updates.
Terri