I set it back to Standby again and tested it with AC or battery mode and waking up with the power button or the touchpad. In all cases, it recovered well while using the Omega driver. This test was done when the computer was freshly started. I wonder if a particular application is linked to the problem. Last night when I found the waking up problem, I MAY have disconnected the TV out in between and I also have an NDAS network drive mounted at home. It is known that if there is any hardware change after entering standby mode (e.g. removing a USB device), the computer may not wake up properly. The NDAS connection actually suggests not to use standby or hibernation when a disk is mounted, however, I found hibernation to be okay.