Unable To Install Programmes

[taichiperson]

I posted yesterday about restoring my old Dell Inspiron 1525 to factory settings, which went remarkably well. However, when trying to install some programmes, I find I can download but not install. I am using Firefox, and when I go to the download folder I have two options on anything I have downloaded - open, or run as administrator. Neither option does anything. I have a trial version of McAfee that shipped with the laptop, and while trying to download Advanced SystemCare that I use on my present laptop I managed to install Slimcleaner Plus - that installed ok, so I wonder if that's causing the problem. I have downloaded all Windows updates but have yet to get Windows Defender to update successfully

Out of that tangle of info, can anyone advise me please?

[SlackAlice]

Some one here doesn't like Slimcleaner plus,

http://malwarefixes.com/remove-slimcleaner-plus/

Are you downloading the correct versions of your programmes to go with your current Windows O/S?

[taichiperson]

On reflection, I have now uninstalled Slimcleaner. As far as I know I'm downloading the correct versions - it's Vista which I know is ancient, but it's an old laptop and my other half is happy with what he knows. I have since posting managed to install AVG - having uninstalled McAfee as I have a current subscription with AVG. I'll post again if I have any more problems.