I created a thread earlier in which I thought we had solved the issue. See here for link:
When downloading from IE9 32 bit out of Win 7 64 bit the downloads don't work. You get the "open, save, save as" but nothing happens when you select any of the 3 options. Download manager doesn't even pop up. This was happening on both win 7 32 bit and win 7 64 bit. We solved the win 7 32 bit IE9 32 bit not downloading (same exact issue) by changing the MIME handling to a 1 from a zero.
See this article: http://technet.microsoft.com/en-us/library/cc749557(v=ws.10).aspx
For the Win 7 64 bit with IE9 32 bit we get the same exact scenario but that fix doesn't work. These systems don't have antivirus or any other applications. Installed from Windows 7 Pro Genuine discs and I made sure the first thing I tried to do was download attachments from emails or anywhere else that we use and nothing is working.
Do not save encrypted files to disk is unchecked, no protected mode etc...
I feel as it's gotta be a registry issue as the fix for the Win 7 32 bit IE9 32 bit works great every time! So why doesn't Win 7 64 bit IE9 32 bit?
If we download from Win 7 64 bit and IE9 64 bit then things work as they should. Download manager pops up and we're good to go.