Screenshots all black?

So I've bought a new PC and it's a lovely black beast. I put Vista Home Premium x64 on it, possibly foolishly - only time will tell.

Here's my problem. On my old machine all I had to do was Alt-Print Screen and paste into a graphics program. That doesn't work at all.

If I do Print Screen and go in to the tga folder all I get is an image which is all black.

Any ideas on how to get this feature working?

That happens to me too. You have turn off anti-aliasing in the video options menu

or use Fraps (www.fraps.com)