is it still the same old laptop?
Nope, the new (HP). Old one (Acer) is dead since November. 3 weeks ago I had a battery change, because of the written problem. Although battery's capacity was okay in some moments (survived 3-3.5 hours without charging), when I moved the computer (really small movements, even a strong Enter pressing was enough), it showed battery is low and switched off - after restart, even BIOS said battery is almost dead. Seemed to be kind of contact error. In the service they said my battery made the same in other computers too - so they changed it to a new one.
The two similarities between the battery breakdowns in May and now:
1, I was playing with EA F1 2002 when the first error appeared.
Theory #1: CPU is probably close to the connection of the battery and the game causes quite a big warmup, so maybe some plastic parts of the fixture are deformed from that heat, losing the perfect connection.
2, In the last period of charging I had to suspend the charge at ~90% because I had to go somewhere and then later I continued it to 100%. (I know it's not that healthy but come on... I take care of the battery, 9 from 10 times I make an almost ideal charge - letting it down to 2-5% and charging to 100%)
Theory #2: simple electric shock... although it's always plugged to a Surge Guard, so it mustn't be that.