I've attempted the install thrice so far and even attempted modifications found on the forums concerning PHP (Aspnet quotes, adding a default user to __config) and taking matters into my own hands by modifying the database directly to add a user account. I am using IIS 7.0 and MySql. The failure actions are different but I noticed a problem the first time, when I browse to http://mysite/ss/admin/ -- it asks for an email address and password, the Web Platform Installer just asks for a "username".

After reinstalling I used an email address for the username and got a tiny bit further. Going to http://mysite/ss/admin/ and entering the email address and password goes back to /security/login with a message "Please choose an authentication method and enter your credentials to access the CMS".. I also noticed that the URL at top becomes:

mysite/ss/Security/login?BackURL=%2fss%2Fadmin

Can anyone point me in the right direction?

I will take that as a "Heck if any of us know" type of answer! ;) In case anybody else gets stuck I will offer my advice:

Do not use Microsoft Web Platform Installer to install to MySQL even if it pretends that it will play nicely. It fails and does not offer any kind of informative response. In fact, quite the opposite really -- it told me the INSTALL WAS COMPLETE.

I was able to install SilverStripe fine manually using my aforementioned setup. I was also able to use WPI (web platform installer) when using IIS7 + MS-SQL.

Enjoy!