To activate it, press F8 twice when you start your computer or hold it. If your mouse or your key board doesn't work, make sure that you have PS/2 connector to both mouse and keyboard. It looks like this: http://www.york.ac.uk/admin/sro/Photos/PS2connection2.JPGSafe mode is to when, windows won't boot up normally and you have to go into safe mode in order to somehow fix it. Its also used to get rid of viruses if windows won't boot up.