Last week, I was installing 4.9.2 on our corporate dev server (II6) and SQL Server 2005. I got the database & folder permissions set up after some fumbling around with the web.config file, and was working through the Install Wizard (custom install) when I encountered an error: Value cannot be null. Parameter name: value

Some searching revealed that the error was likely the result of my having selected to install AD and that I would need to do a complete reinstall to recover from this.

So I "uninstalled" - removed the files from the web site folder, removed the web site itself, removed the database from SQL Server.

And now I cannot for the life of me get the thing reinstalled. I can get to the point of seeing the initial installation page. I can select "Custom" and click "Next". And then I see a page with 2 horizontal lines at the top & links for testing the database connection and going to the prev/next pages. That's all. I can click the link to test the connection and get an appropriate message depending on whether the web.config file contains a valid connection string.

If I go back to the previous page, I either see an error about being unable to connect to the database or a page with an empty dropdown list and a link button.

I've even stopped IIS and deleted all the temporary ASP.NET files on the server, then tried to reinstall. Same behavior. 

This happens across multiple browsers and has been confirmed by a coworker on her machine.

Suggestions?