I have a very simple website that is accessed by a link in a portlet. It is an ASP.Net 2.0 application coded in VB.Net 2005. IE is the "preferred" browser.

On inital load, the website displays a report. The user can click a button to perform a Mime download of an excel file.

Before the report displays, a mixed-content warning is displayed. Getting rid of this warning is probably beyond my control. Also, I have no control over users browser settings.

This is the code I am using for the download:
Response.ClearHeaders()
Response.ClearContent()
Response.Clear()
Response.AddHeader("Content-Disposition", "Attachment;Filename=IRpt.xls")
Response.ContentType = mimeType
Response.BinaryWrite(bytes)

I have the following problem when trying to save this excel file from the download popup:

If I anwswer "Yes" to the warning "This page contains both secure and non-secure items. Do you want to download the non-secure items?", the report displays correctly and the excel file downloads and save correctly.

If I answer "No" to this warning, the report displays correctly. However, if I try to save to Desktop from the download prompt, no file is created, although there is no warning or message. There is an unresolvable link in "My Recent Documents".
If I try to save to My Documents, the file saves correctly. After that, it will save to any location, including Desktop. But if I clear the IE cache with shift-F5, I get the original problem back again.

Can anybody tell me why this is happening, and what to do about it?

Might this be related?

The 'ContentType' differs.