Windows 7 File type icon and application associations not updating on Windows 7 64 bit

Hello,

I am working on a NSIS installer that edits the registry for a couple file types to change their icons and the application that runs them.

After the registry edits are complete I use the SHChangeNotify system call to force the shell to update with the new settings.

; Tell the shell to reset its icon cache
System::Call 'shell32.dll::SHChangeNotify(i, i, i, i) v \
(0x08000000, 0, 0, 0)'

On WinXP 32bit and 64bit systems, this is working fine. It also works fine on a Windows 7 32bit box. However, on a Win7 64 bit box, the file type that is already in the registry is not updating to the new values I set for it. The file type that isn't already in the registry has the proper icon and app association applied to it without issue. Its the type with already existing registry settings that is not updating.

Does anyone have any ideas on this that will update the settings and not require any kind of system restart or killing and restarting explorer, which I want to avoid?

The box I can't get this to work on is Win 7 Professional Build 7600.

Thanks for any assistance.

Greg