Lock up

My new HP 1710, that came with Vista, and over a gig of RAM, keeps locking up....especially when I minimize the browser....even the task manager is affected...I added another gig of RAM, and it still continues...also, I have been unable to play the XM radio player.it tells me I need to install WMP...but then the install tells me that I already have a more up to date version....and can't install WMP 11