key doesn't work

I downloaded Beta when it became public, like most people here. I installed
it on Virtual Server, and had no problems. However, I found that I didn't
like VS very much, so I deleted the image, and decided to start over with
Virtual PC. (I am now aware that a Virtual machine created with VS will work
on VPC, but I didn't know that at the time)

When I began to install it, it got to the point of asking me for the key.
Once I entered it, it thought about it for a minute, then displayed a
message saying that the installation failed. No other explanation. When I
click OK, it just goes back to the window which asks for the key.

I know the key works, because it worked when I installed it on VS. I know I
didn't have a typo. I am stumped.