Windows Vista Unable to install any program

Hi,
Every time I try to install a new program onto my Windows Vista for the past few months the installer starts, but stops installing without any warning or error message popping up, it used to freeze like this at the "registering" step but now it only gets to "preparing to install ".
This has happened with several programs such as iTunes, Skype, and even printer software that I have the driver CD for. Installing Google Chrome worked and I could then download the latest version of Flash Player but anything that requires the actual Windows Installer still freezes. What can I do?
Thanks to anyone who can help!

 

Have you cleaned out your temp directories? I saw behavior like this at my job, and when we cleaned out temp directories iincluding IE temp folders, the problem went away.

 

I am trying to download the newest versions of the programs, (4.1 for Skype and 9 for iTunes), both of which are compatible with Windows Vista. My printer is also compatible with my computer.
I believe the problem is with Windows Installer, (even the Microsoft Fix it tool would not install) is there a way to repair the installer itself?

 

I have tried deleting all temporary folders and nothing changed, thank you for the suggestion though