Hi. Why?

[SPOOK0999]

Hi im SPOOK Today i i have been trying to pay penumbra overture episode 1 (It is not the demo it is the full version) Well i have been having some really bad mouse lag. but what dose not make sence is that when i move around without moving the mouse it wont lag at all. and when i move the mouse it stops for as long as im moving the mouse. But another thing that dont make since is when pick up an object and move it around the screen and area (Using mouse) It wont lag. THIS DONT MAKE SENCE! lol

My specs are E-geforce 6200 256mb ddr2, 768 ram.