When using SSL/HTTPS, an end user using Internet Explorer 6 SP1 cannot download
files.  They receive the following error message: "Internet Explorer cannot
download FileName from WebServer."  Mozilla users can download the same file
without a problem.  It appears to be an IE Bug that is caused by the content
headers Pragma = no-cache and Cache-Content=no-cache.  Tomcat is setting these
automatically, even if the HTML page explicitly specifies otherwise.  

You can easily replicate the problem by setting up a simple HTML file with a
link to a file for download.  Access the page using SSL/HTTPS and click on the
link.  

Here's a debug dump from IE:
sending data:
225 (0xe1) bytes @ 0x1d31768
01d31768  43 4f 4e 4e 45 43 54 20-6a 6d 73 2e 63 68 61 72   CONNECT www.myte
01d31778  74 64 79 6e 61 6d 69 63-73 2e 63 6f 6d 3a 34 34   stsite222.com:44
01d31788  33 20 48 54 54 50 2f 31-2e 30 0d 0a 55 73 65 72   3 HTTP/1.0..User
01d31798  2d 41 67 65 6e 74 3a 20-4d 6f 7a 69 6c 6c 61 2f   -Agent: Mozilla/
01d317a8  34 2e 30 20 28 63 6f 6d-70 61 74 69 62 6c 65 3b   4.0 (compatible;
01d317b8  20 4d 53 49 45 20 36 2e-30 3b 20 57 69 6e 64 6f    MSIE 6.0; Windo
01d317c8  77 73 20 4e 54 20 35 2e-31 3b 20 2e 4e 45 54 20   ws NT 5.1; .NET 
01d317d8  43 4c 52 20 31 2e 31 2e-34 33 32 32 29 0d 0a 48   CLR 1.1.4322)..H
01d317e8  6f 73 74 3a 20 6a 6d 73-2e 63 68 61 72 74 64 79   ost: www.mytests
01d317f8  6e 61 6d 69 63 73 2e 63-6f 6d 0d 0a 43 6f 6e 74   ite222.com..Cont
01d31808  65 6e 74 2d 4c 65 6e 67-74 68 3a 20 30 0d 0a 50   ent-Length: 0..P
01d31818  72 6f 78 79 2d 43 6f 6e-6e 65 63 74 69 6f 6e 3a   roxy-Connection:
01d31828  20 4b 65 65 70 2d 41 6c-69 76 65 0d 0a 50 72 61    Keep-Alive..Pra
01d31838  67 6d 61 3a 20 6e 6f 2d-63 61 63 68 65 0d 0a 0d   gma: no-cache...
01d31848  0a                                                .

While this is really an IE issue, there should be a way to prevent these headers
from being set in Tomcat.  Users can download the file withouth a problem using
Caucho Resin instead of Tomcat as the servlet container.  For additional info,
see the following Microsoft Knowledgebase Article: 
http://support.microsoft.com/?kbid=815313