Have been reading a lot about this one and the picture just gets muddier. I have a 32-bit app that installs a KeyboardHook to wait for a global hotkey and wake up. Running it on Win 7 x64 edition I notice it hangs Outlook x64 edition when the hotkey is pressed.
So I did some research and it looks like 32-bit keyboard hooks aren't even supposed to work in 64 bit apps. Time for more testing...
They hotkey works fine in 64-bit notepad, wordpad, and sticky notes. I verified that these are 64-bit apps since they don't have "*32" next to them in Task Manager. Doesn't hang the app and it does what it's supposed to. But wait... a 32-bit hook dll can't be loaded into a 64-bit app, right?
A look at Process Explorer shows the hook dll isn't even loaded into the notepad process! (If I run the 32-bit notepad.exe from WOW64 directory, I can see the dll loaded into the process, so I know I'm using the tools right).
So the Outlook hanging issue might or might not be related, but why is the hook even working at all in 64-bit notepad?
If that's your ultimate goal, then it's simpler and less of an impact on the system to just use RegisterHotKey.