Unfortunately, I soon hit a wall:
Thankfully, I was given the link for more information in the dialog so that I could figure out the issue. As you can see, the help was.....:
Okay, so there was no more help. I could dig and find the answer to my issue, but I have to step back and ponder for a moment. I've had Flash upgrade on my machine through a variety of versions. I don't recall running into any issues that stopped the install. I'm this install of Silverlight 3 is an exception isolated to me, then no biggie for anyone but me. If it isn't isolated to me, then I think Silverlight is going to lose a few more point to Flash....
Did Silverlight 3 install for you without issue?