I’m using windows 8 dev build and had a similar issue. Silverlight, VMware, and Virtual box were all failing to install. Same issue as in this article.
I had to do a few things to make it work. I took ownership of the temp folder, and I went up to appdata and saw that it was set as read only (….well some kinks are expected in a dev build but…really?) I took off the read only and applied that to all the sub folders. Then I deleted all the temp data as stated above. And now all those programs install just fine.
Now this was for windows 8, but perhaps someone is having a similar problem with 7.