Jerky motion on PC

Hi

I hope this is the right place to go and you haven't heard all this before. The forum search isn't working so I couldn't find out. I have house of the dead 3 on my PC. It doesn't work at all well, the motion is very jerky and slow. You move the cross hair sight and after a second or so it jumps form one part of the screen to another. My utter lack of knowledge of these things led me to increase the frame rate. This seems to have made the gun sight slightly more fluent but the game overall even slower and more jerky. Now, on firing the gun there is a delay of three to four seconds between mouse click and reaction on the screen.

The PC spec is way above what is required to run the game. Pentium 4 1.8 750 mb ram. Every other game I have works OK. Anyone help with this?

got the problem. this is freaky!