Hey,

There are many reasons that you could be facing this problem. Some of which are:

1) Potential Virus/Malware that is causing your system to hang up. - Try running a Local System Scan and delete/quarantine any Suspicious data/executable files u may find.

2) In Windows, there are a lot of temporary files that keep creating whenever you do your daily work like accessing the internet, working on documents. These temporary files basically reside on your computer and keep filling on your disk and tend to slow down your notebook. You can delete all these files. Also you can delete the cookies from your laptop, which again just consume unnecessary space.

HOw to do the above -->

a) Goto Start->Run->%temp% and type enter. Delete all the files in that folder.

c) There is a very good software called CCleaner, (http://www.filehippo.com/download_ccleaner) which I personally like. You can download that software and run it. It would free your notebook of all unnecessary temporary junk files in one shot. You can keep using that software like once a week and keep your notebook free of these temporary, disk consuming files.

3) Another reason your notebook could be slow, is you have installed too many softwares and each one of them resides in your taskbar, even if you are not using them. In such a case they are consuming your Memory (RAM), even though you are not using them at that moment. Now you could disable that and you should see a remarkable difference in the speed of your notebook.

To do that ->

Goto start->run->msconfig and press enter.
A new window would open up. On top of that, there is a tab by the name of "startup". click on that tab. On that page, you would find a button "disable all". I would recommend you do that and restart your laptop.

Lastly but most importantly, If your notebook is still under warranty, please take it to your nearest service center asap. Let them handle the mess :)

I hope all that help.