My Compaq Presario CQ40 (yeah, its pretty old) suddenly turns off after about 1/2 - 1 hour usage without any notice or warning. The power cable and adapter works fine (indicator bulbs show that power is given to the laptop), but it seems like machine suddenly plugged off from the power source. And when I try to switch it on, after the sudden turn off it simply won't turn on. I can only turn it on after letting it to rest for at least couple of hours!

** The battery has been dead for some time now, but it has been working fine on direct power supply until recently.

Has anyone encountered this? and hopefully knows any cure?