Partial declarations, must not specify different base classes

Hi 

I had an ASP.NET web site which was created wothout a solution. I created a solution today and added all the site's items to this solution. Since that, when I try to build a solution, I'm facing with the following error:

Error2 Partial declarations of 'smallbusiness_rtw_cs' must not specify different base classes ~\Site\smallbusiness_rtw_cs\Products.aspx.cs822 smallbusiness_rtw_cs                       

This is the code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class Products : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }
}

Did anyone face wht the same issue? How should I fix it?

Thanks in advance,

Alex