I am not sure what happen to your computer. And I find some reasons for why computer freezes and I hope this info will help you to fix the problem more or less:
1. Computer freezes randomly caused by the hardware
Monitors, power supply and CPU overheat when they are working, so good ventilation is very important. Long working hours can lead to poor power supply or then caused computer freezes randomly. CPU cooling is related to the stability of computers running a major issue, but also thermal failure of the “disastrous.”
Excessive dust inside the machine can cause crash failures. Such as floppy or CD-ROM laser head too much dust contamination, it will lead to read and write errors, can cause serious Computer freezes randomly.
Such as the motherboard and CPU frequency does not match the old motherboard resulting in computer freezes randomly.
Main memory loose, Weld or memory chip itself due to the quality. Exclusion should be based on the specific circumstances of memory access fault, if it is the quality of memory problems, replace the memory in order to solve the problem.
Hard drive failure
Mainly due to aging or improper use of the hard disk caused by bad sectors, bad sectors. This machine is running very prone to crashes. You can use special tools to troubleshoot processing, such as serious damage can only replace the hard drive.
Overclocking the CPU operating frequency increases, while its performance may become unstable. The reason, CPU access to data in memory, already faster than the speed of memory and hard drive data exchange speed, so overclocking is more prominent this conflict, exacerbated in memory or virtual memory can not find the required data in the case, This will be “exception error.” Relatively simple solution of course is the CPU frequency back to normal.
Hardware resource conflicts
Is due to the sound card or video card settings conflict, causing an exception error. In addition, other equipment, interrupts, DMA or port conflict, it may cause a few drivers have exceptions that crash. The solution is based on “safe mode”, in “Control Panel” → “System” → “Device Manager” in the appropriate adjustments. For the driver in case of an exception error, you can modify the registry. Select “Run”, type “REGEDIT”, into the Registry Editor, through the menu under the “Find” feature to find and remove the prefix string associated with the driver all the “master key” and “key” to restart.
2. Computer freezes randomly caused by the Software
The efficiency of a computer virus can make a sharp decline, resulting in Computer freezes randomly.
System files accidentally deleted
Because Windows 9x startup needs Command.com, Io.sys, Msdos.sys and other documents, if these files were damaged or accidentally deleted, even if all the hardware in the CMOS settings are correct will not help.
Destruction initialization file
Because Windows 9x start to read System.ini, Win.ini and registry files, if there Config.sys, Autoexec.bat file, both files will be read. As long as there is an error message of these documents are likely to crash, especially the System.ini, Win.ini, User.dat, System.dat these four documents is particularly important.
Dynamic-link library files (DLL) is missing
In the Windows operating system there is a class file is also important, which is an extension of the dynamic link library DLL files that are from nature in terms of share classes, that is, a DLL file may have multiple software need to call it at runtime. If we delete an application software, the software’s uninstall program will record the files it had installed and ready to delete them one by one, which is prone to be deleted when the dynamic link library files also will be other software used in the case, if the missing link library file is the more important core linked file, then the Computer will freezes randomly, or even collapse. We can use tools such as “Super Rabbit” to delete unwanted DLL files, this will prevent accidentally deleted.
Hard disk space too little or too much debris
If the remaining hard disk space too little then may cause computer freezes randomly, because some applications require large amounts of memory to run, which will require virtual memory, virtual memory is provided by the hard disk, so the hard disk have enough free space to meet the needs of virtual memory. At the same time users have to develop a regular defragment the hard disk, erase junk files in good habits.
Improper software upgrade and Illegal to uninstall software
Most people may think that the software upgrade is not a problem, in fact, during the upgrade process will share some of the components are also upgraded, but other programs may not support the upgraded components which lead to various problems such as computer freezes randomly. Do not install the software directly to delete the directory, if deleted directly, then the registry and the Windows directory will be a lot of garbage there, over time, the system will become unstable and cause computer freezes randomly.
Too Much program from startup
This allows the system resource depletion, so that the individual program needs the data in memory or virtual memory can not be found, there will be an exception error.
Illegal Operation such as Turn off the computer non-normal
Illegal format or parameters using illegal to open or release procedures, will cause the computer to crash. Note to remember the correct format and associated parameters, are not free to open and release are not familiar with the program. Do not directly use the power button on the chassis, otherwise it will cause the system file is corrupted or missing, causing auto-start or run in the crash. For Windows 98/2000/NT other systems, it is very important, serious, can cause computer freezes randomly.
Source: Computer freezes randomly? How to fix computer freezes randomly in windows 7 - Tee Support Blog