RE : Cannot Compile (No suitable method found to override )

Hi, I having been facing problems just after successful testing for a few times. The program just went nuts.
I have four errors :
Error 2 'ASP.signup_aspx.SupportAutoEvents': no suitable method found to override c:\WINDOWS\Microsoft.Net\Framework\v2.0.50727\Temporary ASP.NET Files\project\c9706517\4ddfe966\App_Web_mjh8gy2c.0.cs 

Error 3 'ASP.signup_aspx.GetTypeHashCode()': no suitable method found to override c:\WINDOWS\Microsoft.Net\Framework\v2.0.50727\Temporary ASP.NET Files\project\c9706517\4ddfe966\App_Web_mjh8gy2c.0.cs 

Error 4 'ASP.signup_aspx.ProcessRequest(System.Web.HttpContext)': no suitable method found to override c:\WINDOWS\Microsoft.Net\Framework\v2.0.50727\Temporary ASP.NET Files\project\c9706517\4ddfe966\App_Web_mjh8gy2c.0.cs 

Error 5 'ASP.signup_aspx' does not implement interface member 'System.Web.IHttp ...