Do you have CustomError enabled on your application?
When uploading or creating a project, VS.net 2003 makes an http call to a non existing page, get_aspx_ver.aspx, to get the http header. VS.net 2003 uses this as a mechanism to determine the version of the framework.
If the CustomError is enabled with web.config to direct all errors to an HTML page (or any page that are not mapped to ASP.net ISAPI), VS.net 2003 will not be able to determine the version of the framework and thus disallow the upload process.
To fix it, either get rid of CustomError or point the customerror page to an ASPX page.
Bruce
DiscountASP.NET: Developer Ready ASP.NET Web Hosting
- Microsoft Gold Certified Partner
- Voted 2007, 2006 & 2005 Best ASP.NET Web Hosting by asp.netPRO Magazine