I had Java JRE version 6.20 installed on another partition other than the system partition. The directory was accidentally deleted by a bad software install of another program. Since then, I cannot reinstall it as it says it is already installed. I also cannot uninstall it. I removed the Java MSI installer packages with Windows Install Cleanup and this did not help. I have also deleted everything I could find related to Java, but could not delete the folder in C:/Program files (x86)/Common files. I have also done a lot of registry cleanup as a number of other directories were also deleted.
When I try to run the manual installer for the same package, it says that it is already installed and gives me the options to reinstall it. When I click on that, an error message comes up saying that this only applies to programs that are already installed.
I had the same issue with my HP printer driver, but it looks like the MS drivers will at least do printing and scans. So I have given up on trying to reinstall those drivers.