Re installation may fix it but only if you are willing to , also you can clear CMOS but no guarantee . Some time it may be a small glitch , try to troubleshoot this problem step by step .
One of the first action I do after install the OS on my laptop and laptops of customers as well(!), is, that I go to the Control Panel and adjust the Power Plan to my need for either Battery and Power On working. I never had problems with connect the power adapter while the laptop were running in full mode. By the way, if the laptop used is an Acer Laptop, you should have the Acer Launch Manager installed which works fully in background and helps to had the laptop up and running correctly with the Acer hardware and drivers. The Launch Manager isn't needed but recommended to run.
Have to say thats never happened to me. Pretty strange.... Can it have something to do with Hybrid Sleep?
Hybrid Sleep = S3+S4 state, AFAIK. The system saves a hibernation image onto the disk and enters S3 standby (Suspend to RAM) state after. If the power fails it works like waking up from Hibernation, else it's a normal S3 wakeup.
I don't fully understand everything no. But doesn't the charge/battery device trigger some ISR when the charger is connected? Or are all interrupts ignored when in sleep, except for the ones that are supposed to wake the pc up?