I have a HP dv7-1245dx. Sometimes when I close my laptop (I don't shut it down) the light will go off like its supposed to do, but then will come back on a few minutes later (this happens when the laptop is still closed.). I have had this laptop for about 2-3 years. It has been dropped, but did not sustain any damage and I did have to take it to get repaired after a virus found its way in and I could not get rid of it. Other than that I haven't had any problems, except for this laptop coming on automatically problem I'm currently having. This problem started back in March of 2012. Any tips on why this is happening and how to fix it will be greatly appreciated.
Any number of programs could be waking it back up, because your laptop is not off, it is likely going into suspend mode where it can wake up from just about any input (like moving the mouse) or by some programs.
You can go to your power management features and adjust what your laptop does when you close the lid, my guess is right now it goes into "Standby" mode, if you change this to "Hibernate" mode it should fix your issue. Hibernate mode will take a little longer to come back when you open the lid back up (and you'll have to press power instead of just pressing any button), but if you usually leave your laptop by just shutting the lid, I would recommend setting it to hibernate mode.
Your laptop will also use less power this way, as standby mode uses power to keep your laptop on somewhat, hibernate actually lets the whole laptop turn off, but it restores all your programs to where they were when you closed the lid when it comes back up.
The easiest way to get to power management is to right click your desktop, select either personalize (win7 and maybe vista) or properties (win xp), go to the screensaver section and click the power management option. From there, go to the advanced power settings menu, and scroll down to find your "when i close the lid option"