Ignore that last post !!
So... you're trying to access the the site and you get an installation screen?
2 possible issues here..
1. you've got a db log file in \App_Data
2. You have .Net Framework cache issue(s)
If you have a database_log file in your \App_Data folder you need to delete it.
1. Close all web browsers into the web site
2. Open your "Task Manager" and find w3wp.exe, right click on it and select "End Process"
As long as no w3wp.exe process is running on the machine hosting the site, and where the database is located, you should be able to open the \App_Data folder and delet ethe database_log file
Next, go C:\Windows\.Net Framework\
Shell down to the \Temp folder for v2.x and v4.x and delete EVERYTHING below \Temp
Now, restart your IIS via the cmd line IISRESET at the prompt
Hit the site again...