WebMatrix3 HTTP 500 with Starter Site

Hello Everyone

I apologise in advance if this is a duplicate post.

This is what I did:

1. Upgraded from WebMatrix2 to WebMatrix3
2. New Site from Template Gallery
3. Filtered by PHP (2 Sites remained)
4. Selected Starter Site
5. Gave it a unique name
6. WebMatrix auto downloaded start site template for me
7. Entered Site Admin's Password (twice)
8. WebMatrix installed the site 
9. Clicked the Run Button
10. Received a HTTP 500 Error Message
11. Looked online for an answer
12. Uninstalled WebMatrix3
13. Tried to reinstall WebMatrix2
14. The webinstaller for WebMatrix2 installed WebMatrix3 (!!??!!!)
15. Rebooted PC
16. Repeated Steps 1 - 9
17. Received a HTTP 500 Error Message (again)
18. If I repeat Steps 1-9 but I pick ASP instead of PHP then everything works perfect

Can anyone help?

Cheers :-)