Hardware Conflict

• When your laptop boots up, it checks all the various installed components. If the drivers from two components conflict with each other, the laptop will essentially become “confused” and freeze because it simply does not know how to handle the problem. A laptop that suddenly begins freezing after the installation of a new component, such as a new printer, is most likely experiencing a conflict in software between the new addition and something previously installed. Try disconnecting the new component and booting up to see if the problem persists.
  
  

Corrupted Registry

• Your operating system's registry holds important files necessary for starting your laptop or other programs. If any of the files within the registry become corrupted or damaged, it could affect the way the laptop boots or operates afterward. Boot the laptop into Safe Mode and run a registry scanning program to repair any errors that may be preventing proper operation of your machine.
  
  

Malware

• If your laptop starts behaving strangely for no apparent reason, there's a good chance a malware program is lurking somewhere on your system. Malware arrives on your laptop in the form of viruses or spyware, and typically runs in the background of your laptop without your knowledge. These unwanted intruders can, and often do, spell trouble for your machine, as they infect important files and programs to render them unusable. While in Safe Mode, run a malware scan to seek and destroy any unwelcome “guests” taking up residence on your laptop.
  
  

Program Startup Problem

• Sometimes a startup problem appears due to the properly installed programs on your laptop. Some programs are configured to automatically start when your computer boots, which can cause an issue with another program at startup. After booting in Safe Mode, check your System Configuration Utility by typing “msconfig” in the Run box under the Start Menu. This will open a dialogue box that will show all the programs that load when you boot, listed under the Startup tab. Make a list of everything that has a check mark beside it before unchecking them all and rebooting. If the laptop starts fine, one of these programs was causing the trouble. Start rechecking the various startup programs and rebooting until you encounter another freeze. You've found your culprit. Try reinstalling or updating the program or removing it entirely to eliminate future freezes.