Most likely your IIS settings for this Virtual Directory forbid a file with this extension to be browsed to. I got 404.7 error attempting to open a file in IE when I browsed to the URL: http://localhost/mysite/myvbfile.vb
Using your browser, try to open the same URL that your VB program is attempting to access. I anticipate that you will get the 404.7 error in the browser window too.
You have two approaches here:
- Have your PHP script write the file to a location outside of IIS where your VB.Net program can access.
- Modify the Request Filtering in IIS for your site so that this file can be browsed. (screenshot) http://support.citrix.com/article/html/images/1CTX132655-1.gif