Software does not take installation

I installed Windows 7 today. After I installed it I updated it in the Internet and I am trying to install some necessary software. But it does not accept installation. I was listening to some music & it stopped abruptly. I thought it is a common factor so, I restarted it and tried to work again but there is still the same problem. I lost my temperament and set again the operating system. Now it has improved slightly.
I installed Avast Internet Security but the same does not open.
Realtek High Definition Audio Software was also installed & it is working but I am having problems with Antivirus. I also tried to install Kaspersky. Does not work.
Now what should I do? Do I format Windows?
