sound like you have onboard graphics,they may not be up to the job.
if you can get as far as the game settings screen then choose the lowest screen size 640x480 or 800x600 and turn of any fancy effects.
theme pk is not very demanding though and should play ok on your system,scrolling may be slow at 1024x768 or higher though.
what is the make and model of your computer and will have a look and see if there is a graphic driver update for the chipset.
alternativly get click here and it will tell you which chipset and even give you links to driver updates that may well help.
most newer games wont play well if at all with onboard graphics,aida will also tell you if you have an agp slot,then its just a case of buying a graphics card to upgrade.