When submitting a multipart web-form over an SSL (https) connection, using IE 6 you might run into this errormessage immediately after pressing "submit":
The page cannot be displayed
The page you are looking for is currently unavailable.
The Web site might be experiencing technical difficulties,
or you may need to adjust your browser settings.
[SOLUTION]
Although I haven't found a solution for this problem, yet - I've found some interesting references:
Microsoft Knowledge Base Article #815764
Microsoft Knowledge Base Article #822753
Newsgroups:
Microsoft.public.windows.inetexplorer.ie6.browser
macromedia.coldfusion.advanced_techniques
Microsoft.public.site-server.postingacceptr
They all seem to boil down to: This is a bug of IE which hasn't been fixed, yet.