Cannot debug ASP website on IIS 6.1

I am new to our company and just trying to set up my workstation. We have an ASP website I am trying to debug in Visual Studio 2010. In the "Web" section of the project properties we have the "Use Local IIS Web server" option selected, however when I try to debug the page I'm working on I get the error "Unable to start debugging on the web server. See help for common configuration errors." I can see the site in IIS (Under Sites -> Default Web Site -> SiteImWorkingOn), and both IIS and the VS project are using .NET 4.0. Any suggestions?

EDIT: I should mention that I've run the "aspnet regiis -i" command in the command prompt to make sure IIS was running .NET 4.0

SECOND EDIT: I found that ASP.NET was not turned on, after doing this I am getting the following error:

HTTP Error 500.19 - Internal Server Error
The requested page cannot be accessed because the related configuration data for the      page is invalid.

Module IIS Web Core 
Notification BeginRequest 
Handler Not yet determined 
Error Code 0x8007000d 
Config Error  
Config File \\?\C:\Projects\sym_Periscope_NEAL\Periscope\Web\web.config 
Requested URL http://localhost:80/Periscope/Pages/Dist.aspx 
Physical Path C:\Projects\sym_Periscope_NEAL\Periscope\Web\Pages\Dist.aspx 
Logon Method Not yet determined 
Logon User Not yet determined