Computer refuses to start in SAFE MODEs because of hardware changes?

I WANT TO SCAN IN SAFE MODE, BUT IT WON'T START IN SAFE MODE, NOR SAFE MODE WITH NETWORKING NOR THE OTHER MODES. it only starts in normal mode. WHEN I PRESS SAFE MODE, IT RESTARTS AND SAYS IT ENCOUNTERED A HARDWARE CHANGE. THEN IT STARTS IN NORMAL MODE after a countdown. PLEASE HELP