On Windows 7 I’ve always chosen to open Internet Explorer (64-bit) rather than the standard 32-bit version. This is in the hope that because the former is both older and more popular it might be more subject to vulnerabilities. Whether that it true or not I don’t know, but it’s worth it right…
Note that there is some downsides 64-bit. For example in SkyDrive trying to open an office (Word/Excel) file for edit locally fails (maybe because the target apps are 32-bit).
Anyway, a while back, don’t know quite when…maybe with the upgrade to MSIE 10 that ability was lost. I still use the Internet Explorer (64-bit) shortcut but the MSIE copy that opens is 32-bit. How do I know? Well I use Aaron Margolis’s PrivBar which shows that amongst other things. The screenshot below shows it reporting “32-bit” along with “Low IL”, and my userid.
I’ve never got around to investigating that until now. But after some googling I think I’ve found the answer…
In short set “Enable Enhanced Protected Mode“, reboot and then you’ll find 64-bit mode is back.
I’ve only been running in this mode for a little while but it seems good.
For more details see the following articles. The search returned the first article and based on that I found the Microsoft articles; the first is general, the second’s more about the internals, and the last is aimed at the developer of plugins.