Upload file to a URL with Password and Username

Hi

I currently have a form that contains an active-x control which uploads a file to a URL which has a username and password embedded in it.

I was using :
strURL = "https://username:password@organisation/form.pl" 

WSIEBrowser.Navigate strURL, , , bFormData, "Content-Type: multipart/form-data; boundary=" + strBoundary + vbCrLf

If I use Google Chrome and manually enter the URL (with username and PW embeded) all is fine.  If I use IE and try the same then I get an error.  For IE I have to modify two registry keys to be able to manually navigate to the URL.  Hence I believe the problem to be the way Windows handles the URL with embebed security details.  

I was wondering if there was another way round this?  I don't really want to have to modify registry keys on my client's machines.

In case you are wondering, the file i need to upload will always be of a known name and in a known location.

Many thanks

Kim