Problem installing programme

[bruce 13]

I have Windows 7 64 bit ultimate. It recently displayed problems installing programmes. First it was the drivers for the microsoft keyboard, then itunes. I decided to do a windows safety scan to check for registry errors, it would not install. All programmes do the same thing, begin to install normally then stop, in the case of itunes it displayed the normal procedure till close to the end of the installation then rolled back the installation and displayed a message saying no files have been changed. I have turned off windows notification, tried the virus protection turned off and run as administrator, nothing has worked. does anyone have any sugestions?
thanks
Bruce

 

[richc46]

Welcome
Run a full anti virus scan
Download and run a full scan with malwarebytes (update first)

Try with a clean boot
How to Troubleshoot a Problem by Performing a Clean Startup in Windows 7 or Vista

Try in safe mode