Reformatted Vista Laptop....now slow/freezing at times.

Hi guys...i ran into some difficulties over the last few days with my laptop.

It was slow to respond,and there would be ghost images or sillouettes of an application that I tried to minimise.

I thought reformatting would change this and while it is somewhat better some webpages and programs still freeze up etc. (I probably should have come here for advice 1st.)

Here is an image of what sometimes happens. I had a program running and placed on top of a webpage and when I go to minimise it it leaves a "blank" space where it was placed. I'm also getting the (Not Responding) at the top of web pages and programs more often than not when I go to close/open anything.

Thanks for your advice.