If you haven't discovered this by now, you will. Never, never, never, name a page or control, Login. It just won't work. Maybe it will work in the IDE, but not a chance in hell when you precompile the site.
CS0030: Cannot convert type 'ASP.login_aspx' to 'System.Web.UI.WebControls.Login'
Source Error:
Line 118: public login_aspx() {
Line 119: string[] dependencies;
Line 120: ((Login)(this)).AppRelativeVirtualPath
= "~/login.aspx";
Line 121: if ((global::ASP.login_aspx.@__initialized
== false)) {
Line 122: dependencies = new string[2];
An error similar to the above is what you will always get. Rename the class inside your page or whatever to get around this annoying issue.
Read the complete post at http://www.dotnettipoftheday.com/blog.aspx?id=302