Ok, mind elaborating a bit on how problem can be fixed?
While AngelIsrafel's description can work, it can also incur a lot of work. You don't need to have the exact makes and models of your hardware components. You
will need to know the CPU make and model, video card model, the type and number of system RAM modules that are installed in your computer, and the power output--in watts--of your PSU. (For OEM power supplies, do a search for your precise model and check the system specs. Most will show the PSU's output in watts.) Once you have that information, you can go here:
http://www.msi.com/service/power-supply-calculator/
The first set of inputs require the precise make, processor modell, CPU core name, and core sub-model. You can ignore the CPU code.
The second set of inputs is for the video card vendor, model, and number of installed cards. Note that some model lines are unavailable, so choose the one that's closest to the one installed in your computer.
The next group of inputs are for optional PCI cards, PCIe-X cards, and various storage. Each of these draw power from the PSU, so select accordingly.
External devices: Count the number of USB or IEEE 1394 (Firewire) external devices which are connected and do
not have their own power supplies--for example, most external HDDs and optical drives have a power brick of their own and do not draw power from the computer's USB/Firewire connection.
Memories: This is where you need to know the exact type of system RAM modules and the number which are installed.
Others: Lastly, the number of fans inside your computer and if you have a front bay card reader. Count the case fans and CPU fan, but
not the PSU or GPU fans--the CPU fan is powered from the system board, the PSU and GPU fans are already taken into consideration.
Compare what the PSU calculator shows against the advertised nominal output of your PSU. The calculator will show the power draw at 80% load. I myself recommend having 80-100 watts of reserve power available, just to be on the safe side.
PSUs age and downgrade over time and the amount of usage--or abuse--they receive. Better-quality PSUs will last longer and take more abuse and strain than lower-quality PSUs. This includes OEM power supplies, which tend to be of average or lower quality.
And also do note that if you're using an OEM power supply in a computer which isn't marketed as a premium or gaming machine, chances are that the PSU is going to be a bit on the weak side, output-wise. Average industry standard for newer computers is approximately 350W. Older, and especially for "value" computers is 250-300W. YMMV here.