I am agree with riider. There is no hp4570c scanner driver for windows 7, so I think you need to install a windows Vista driver to compatible with the windows 7 system. If your system is 64 bit, you need to download a 64 bit vista driver. And if your system is 32bit, you need to download 32 bit vista driver.
You can following This PC > Properties to see your system version. And of course, the HP official site will auto-detect to told you which system version your computer is.
I do not find an article about to install compatible scanner driver, but here is a compatible printer drivers installation guide, I think the steps is similar. So I think maybe this article will help you when you install the scanner drivers:
Wish it helps.
message edited by jerfrank