Recently i came across a really strange problem with my laptop.
It all started when i left it in hibernation mode and it run out of battery while in hibernation. When i plugged it into the power cord and opened it started behaving strangely. In particular its keyboard seemed unresponsive and its touchpad also. Thus i couldn’t log in. After a while i realised that if i kept a key pressed down long enough it would write it (really slow). At first i suspected a virus or something that could generate too much load to make it delay that much. It wasn’t so. In safe mode the problem seemed to disappear.
The solution to all above was to remove the laptop’s battery and only boot with the power cord! Everything was again back to normal. I can only give the explanation that the battery has been ‘damaged’ somehow due to the last hibernation and it caused the system unresponsiveness. In safe mode the system due to fewer drivers (or other drivers) seems that it bypassed the problems it ‘detected’ regarding the battery with no impact on the system.