logitech Web cam not working - any ideas?

ive got a Dell inspiron 531 - just bought 3 weeks ago running windows Vista home premium, 2gb RAM, nvidia geforce 8300GS video card.  i also bought, not from dell, a logitech communication STX web cam.  downloaded the latest drivers from the logitech web site but i still cant get the cam to work.  seems to install fine but all i get is a purple screen - sound seems to work fine though.

 

not sure if the issue is vista?  the drivers for the cam say they are vista compatible i am guessing because it shipped 3 weeks ago the video card is using the latest drivers - but will need to check.

 

anyone any ideas?

 

thanks