I had the same problem and ran across your message while searching for solutions. I solved the problem about 5 minutes after reading your message, so I thought I'd come back here and let you know. It's several months after your posting, so I don't know if you'll get this, but here it is anyway...
Another website pointed out that the error message from the installer is completely misleading, and that the real problem is that the installer can neither access nor create "c:\temp". Well, my machine already has "c:\temp", but I started wondering if the name of the "c:\temp-mysql" directory from which I was trying to install might not be the problem. It seemed like a long-shot, but I changed it to "c:\tempsql" because that's shorter than 8 chars and doesn't contain any punctuation.
Sure enough, c:\tempsql\setup.exe runs. Have you unzipped the MySQL distribution into a path with long names, spaces, or anything like that?
Hope this helps somebody...
Adrian