There is really not sufficient information here.
This could be caused by a whole bunch of things.
One thing you might try doing for starters is to boot to safe mode and shut down from there. If the problem persists, it eliminates any hardware source for your problem.
Then I would suggest that you take the following steps in the following order:
1. As others have suggested, get Piriform's CCleaner and run it. You do not necessarily have to clean the registry at this time.
2. Scan your entire system with your fully up-to-date antivirus.
3. If you do not already have it installed, get Spybot Search and Destroy, run its update program (yes, even after you've just installed it from current distribution), and then run it to scan your system for spyware, removing whatever it fines.
4. Remove all unused or garbage software from your machine in the usual way via "Uninstall a program." Before you remove them, note the folder in which the executable resides (this is not always intuitive). Then remove any of those folders that remain in your "Programs" directory.
5. Run CCleaner again, including its registry cleaner, which will remove all the remnants of the applications you just removed.
6. Obtain a good third-party disk defragmenter and run it. Others have suggested Auslogic or Piriform; I have not used them but by all accounts they are good products. I paid for Raxco's PerfectDisk and I KNOW it's a good product. First run the disk defragmenter. If it has a system area defragmenter (which requires a reboot), run it next, then run the disk defragmenter again.
7. Shutdown and reboot. Shutdown again to see if the problem persists.
If it does, well, I would run a system file check. To do this, open as administrator a command prompt window and type "sfc /scannow". Have your Windows distribution disk ready (this is not necessary if your O/S was correctly installed and configured, which on laptops they usually are).
If the problem does persist, then things get complex. It would be a good idea at this point to reflash your BiOS with the current version. This is MUCH easier and safer than it used to be -- it's just like installing software now. You just need to identify the correct update at your motherboard manufacturer's website.
If that doesn't work, get a good piece of driver scanner software and make sure all your device drivers are up to date, and update those as needed. The WinZip guys make a decent software for that, but it isn't freeware.
Now, if the problem still persists, things get REAL complicated. First check your msconfig and see what starts up. There are a lot of what we in the Unix world used to call "daemons," applications that constantly listen in the background for input. Some of these are safe to kill, some aren't. Someone else mentioned realsched and qttask -- these are certainly not necessary but seldom would cause this problem. But when you see questionable ones you can look them up online and see if they're safe to kill.
You can look in your task manager while your system is up and running to see all the applications and services that are running. Identifying the culprit(s) from the hundreds of items on these lists is truly a daunting task, though. Hopefully your problem will be solved before resorting to this.
It should not be necessary to edit your registry. It used to work right, right?
Hope this helps.