I have a small vaio (10"), without cd, running on windows 7.
After installing McAfee antivirus program, upon re-start the computer shows blue screen. When starting in safe mode I tried to restore without success.
Please, can somebody help? What can I do to restore windows 7?

Turn off the machine. Now turn it on and keep pressing the "F8" key every second. Just above Safe Mode you should get a startup and repair option. Aftr you've run it you should get a option for "advanced options" The link for advance options is not a button. It looks like a web link.
On the next page you should get "System Restore". Try running it from here...