[Red Tek BSA]

I got a big problem. i got a working copy of medal of honor spearhead. it works at 2 other pcs with no problem but at my pc it doesnt. everytime i try to install it it doesnt even get to the point where i have to enter the cd key. the step right before that when i klick next it says "The registration number was not correct. the instalation cannot continue" and it quits the setup. does anyone know whut to do about this???as i said the coyp is working. i installed it at tow other different pcs. PLEASE HELP!!!