Can’t Power on from Stand By mode

If I don’t have work in progress, I use the “Stand By” mode to turn off my computer. This allows me to (sometimes) restart the computer quickly.

1/3 of the time when I re-start the computer… I’m greeted with a blank screen and no hard drive activity. I have tried using the mouse/keyboard and waited up to 30 minutes to see if the computer would start up. Eventualy I am forced to hit the reset button to get the computer working.

Any suggestions as to why Stand By mode works erratically? TY for any assistance with this annoyance.