Laptop Charging Problem?

hi guys!

i recently observed this problem on my ECS-G556E laptop. for two times i worked on batteries at levels reaching up to 70% of full charge then plugged my unit on AC power to charge it. at about 80% i decided to turn off my laptop and leave it to charge to full battery power.

since it was late at night i decided to sleep and i left my unit to charge overnight (for about 5 hours i think), thinking that when i wake up the LED charging indicator would turn off (as it did previously). but it did not. so decided to turn on my unit to check at windows xp if it is still charging at some percentage level. but the LED charging indicator turned off, which means that the battery is fully charged.

this afternoon also i turned off my unit at a 51% charge level and plugged it in AC power to charge it. but now after 4 hours the LED still does not turn off. i think it is more or less two hours to charge a Li-Ion battery pack at 50% level right?

what could be the problem here? is it the charging circuit already? i just had my unit for less than half a year. help please!

thanks in advance!