I am having an intermittent issue with my screen not waking up. It goes to sleep after 10 minutes normally but just occasionally it doesn't come back on. usually I have to reboot the pc. I tried a different monitor which worked fine, when I reconnected my normal monitor it also worked fine. The monitor power light flashes to indicate its in sleep mode but doesn't want to wake despite moving mouse or pressing keyboard. The graphics card is only a couple of months old and the screen is over 5 years old. This problem only happens maybe once a month, the rest of the time it works as normal. Any suggestions gratefully received.