Open your web.config. Look at the <authentication> tag and check the mode. Is it set to "Forms"? If so, change it to "Windows". This *should* work. Note, however, that anybody running that page will run as aspnet user. You can use impersonation to impersonate an account with less privileges. Now, don't judge me on this but this probably makes sense since you're uploading data to the server, i'd imagine you have to be able to do this as a privileged user, hence the windows authentication mode. Hope that helps.