IE8 won't download a file with a custom mime/type with UAC enabled

Question

I have a .net service running on the local machine (Windows 7 x64, IE8, .net 3.5, C#) that returns a file to the browser in response to a user action. Using firefox or chrom

Answer 1

For me the solution to this problem was changing

Response.ContentType = "application/vnd.ms-excel";

to

Response.ContentType = "text/csv";