Hi,
Sjaak postet a few days ago a workaround for opening files with Chrome. I played a little bit with mod_headers and found a tweak to remove [1] from file extension, when using IE9 and Connections.
You need mod_headers and mod_setenvif:
<IfModule mod_setenvif.c>
SetEnvIf User-Agent "MSIE 9\." IE9
<IfModule mod_headers.c>
Header edit Content-Disposition "^(.*)filename\*=UTF-8['a-z]{4}(.*)$" "$1filename*=$2" env=IE9
</IfModule>
</IfModule>
After this the Content-Disposition header line shows
Content-Disposition: attachment; filename*=%43%41%54%20%53%63%68%6c%c3%bc%73%73%65%6c%2e%65%6d%6c; size=7637; creation-date="Fri, 30 Dec 2011 10:44:20 +0100"; modification-date="Fri, 30 Dec 2011 10:44:20 +0100";
without mod_headers:
Content-Disposition: attachment; filename*=UTF-8'en'%42%6f%6e%75%73%20%53%79%73%74%65%6d%20%76%32%2e%70%70%74%78; size=2563575; creation-date="Fri, 2 Mar 2012 13:37:39 +0100"; modification-date="Fri, 2 Mar 2012 13:37:39 +0100";
I only remove UTF-8'de' and IE9 doesn't add [1]. I tested with different installations and languages, so i think it works, but please test it in your environment first.
Regards and thanks again to Sjaak.
Christoph
Update: I posted more details on my blog:
http://www.stoeps.de/ibm-connections-file-download-with-ie-9-without-1-on-extension/