Assistance required with ASP.NET compilation error

I have an intermittent compi开发者_StackOverflowlation error on an ASP.NET File System website that I have created in Visual studio 2005, using C# as the language and running on the ASP.NET development server.

This website usually compiles with no problems/errors. However, the page containing a FileUpload control (which works correctly most of the time) will sometimes fail compilation with this error:

Compilation error CS0117: 'FileUpload' does not contain a definition for 'HasFile'

I have checked everything I can think of to resolve this problem, including re-adding the control to the aspx page, checking for the correct using/namespace declarations, checking the code behind syntax to declare/use the FilUpload control etc. But to no avail.

When I have been patient enough to continually re-compile the site it will eventually compile. Sometimes this is immediate, but can take literally dozens of attempts.

Can anyone offer advice on this problem? Any help would be appreciated.