There are numerous potential issues that can cause your laptop to freeze, there are three that are both most common, and also account for the vast majority of stalls and stutters. The good news is that these are also the easiest for the average user to address.
The first cause is physical—laptops will often (somewhat paradoxically) freeze when overheated. Whether it's dust built up in the chassis and vents or a blanket preventing airflow, rising temperatures can put the kibosh on your late night project or marathon Netflix session faster than you can say toasted leg syndrome.
The second frequent freezer is insufficient memory. A laptop's RAM is much like the working memory of the brain, used to hold data short term while it's accessed for a variety of programs and functions. Run out of RAM and you'll find yourself running into issues, including slowdowns in performance, stuttering during processor-intensive tasks, and even full blown lockups and blue screens.
The third and final cause of laptop catatonia can be loosely labelled "software problems." This is a big umbrella that encompasses everything from BIOS changes to software bugs to malware and viruses.
Whatever the root cause may be, when you're staring down a paralytic PC, the initial steps to take are the same. First, try to close the offending program. If only one program is having issues, closing it will often temporarily solve the problem. But closing the program may be more difficult than just clicking the X in the corner.
If a program is unresponsive, try closing it through the Task Manager. You probably already know that you can access this tool by pressing Ctrl+Alt+Del, but for a quicker route, you can also use Ctrl+Shift+Esc.
If your laptop won't even let you do that, then it's time for a hard reset. On most laptops, you can do this by pressing and holding the power button for a few seconds longer than usual—just hold the button until the device powers off. If this doesn't work, you may need to do it the hard way—by disconnecting the AC connection and removing the battery.
The next thing to do is check is the temperature of the laptop. While most people don't have a Fluke IR thermometer handy, the touch test is usually sufficient. Feel the laptop chassis, but be careful, because it may be hot to the touch or even hot enough to burn. Hotspots are common around the vents and hinge, and on the underside of the system. Also do a visual inspection of the vents. If there is anything obstructing airflow, the heat buildup may be causing the problem.
Fixing and Avoiding Problems
Heat problems can often be addressed simply by cleaning out any dust with a can of compressed air and keeping the vents unobstructed. In other instances, however, you may have a bigger problem, such as a broken cooling fan, or a heat sink that needs re-seating. These fixes can sometimes be tackled at home with the right tools and some Googling for tutorials, but if you don't know what you're doing, you might want to take your PC to a professional before trying to open up the chassis yourself.
To ferret out memory problems, start by finding out where memory is being used. In the task manager, select the "Processes" tab. You'll then see a list of all the various processes running on the machine at any given moment. Without opening any programs, take a look at the percentage of physical memory being used. If a large percentage is already in use with no programs running, you've likely found your problem. If your physical memory is mostly free, try opening the last program used, and then open one program at a time to see if any of your frequently used apps are hogging all the memory.
You can also run a memory test using the Windows Memory Diagnostics Tool, found by opening the Start Menu and searching "memory." Run the diagnostic, which will involve an automatic reboot.
If your memory is mostly full, you'll want to free up some space. While freeing up RAM could easily be its own series of articles, the essence of it is this: Unnecessary files, programs, and background processes will eat up your available RAM, leaving you prone to slowdowns and freezes. To fix this, shift files to the hard drive, uninstall programs that aren't needed or used, and turn off any programs running in the background. Unsure of how to do this? Take a look at our guide, How to Remove Bloatware. To prevent future problems, make the most of your memory by cleaning up and defragging your hard drive, and consider upgrading with more RAM.
If the problem has its roots in software, be it a malicious program, a buggy software update, or corrupted driver, there are two simple steps to take. First, revert your PC to a previous state using System Restore, also found in the System Tools folder. If you can pinpoint the date that your performance issues began, you can simply roll back your system to a prior date.
Once you've reverted to a more stable version of your system, head off future problems by updating your drivers and running a virus scan.
If these simple steps aren't enough to alleviate your frozen laptop woes, you have two options. Often solutions to specific problems can be found with a bit of Google-Fu—you can diagnose a lot of problems just by knowing the symptoms and the make and model of your laptop. Don't hesitate to contact the manufacturer's tech support, either. Many problems will pop up due to system specific issues, such as a known software bug or flawed component, and they will be able to not only help you determine what the problem is, they will also be equipped to help you fix it (assuming of course that the laptop is still under warranty).
The second option is to approach a local repair shop or technician. There are literally hundreds (if not thousands) of potential freeze-inducing problems that can arise in one laptop and a bit of knowledge will go a long way toward figuring out what that problem is and how to fix it.