>Is your application setup distributing the MSCOMCTL.OCX? Is this with a merge module or MSI that will not overwrite a newer version? I do not distribute this as I have not had to in my setup -- seems to already be included in Windows. Possibly there are multiple copies installed and this is causing the problems...

Last time I had to mess with the InstallShield (IOW in the cenozoic before Inno) it was simply refused as something belonging to the OS and not overwritable. However it's quite possible that some older versions of it would gladly install it elsewhere and create the mess.

Start searching and don't trust anything called explorer to show you files of such sensitive nature. Use something more reliable, like Total Commander. And expect surprises with both ocx and the underlying dll.