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When I run a 32-bit program in Windows 7 64-bit often times a 64-bit process is started with a 32-bit process underneath it. For instance, if I start iexplorer.exe (Internet Explorer) from C:\Program Files (x86)\Internet Explorer it starts a 64-bit process with a 32-bit process underneath it.


This can be seen in Process Explorer as well as Task Manager.


Why is this? What's going on here? Also, if I go to C:\Program Files\Internet Explorer and start iexplorer.exe from there, again, both a 64-bit and a 32-bit process is started. The executable in this folder is supposed to start a 64-bit version of the program.

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That's by design to ensure 32-bit add-ons (e.g. Browser Helper Objects (BHOs), toolbars, and ActiveX controls) work as expected. The main manager process always matches the operating system bitness, but tabs can be either 32-bit or 64-bit processes. If you want IE to be fully 64-bit you can enable the Enhanced Protected Mode. – and31415 May 3 '14 at 9:54

If the 64bit application needs (or thinks it may need) to interface with 32bit applications, modules, or processes, it'll spawn a 32bit process to manage that interaction.

In the case of IE, as was mentioned in @and31415's comment, it needs to interact with add-ons (such as Flash, ActiveX etc.) as well as other applications that may be needed, based upon the content you browse).

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