esutton

It is not a dependency issue under Vista; at least in my case. It is security issue preventing the DLL from being registered normally using regsvr32.exe. Here is s a work around you can use to confirm: 1. Start Windows Explorer ( right-mouse click on Windows Start button and select Explore OR hold down the 'E' key and press the Windows logo key button on your keyboard ) 2. Right-mouse click on C:\Windows\System32\cmd.exe and select Run as administrator 3. At the command prompt, enter regsvr32 mscomm32.ocx My old C# .NET 1.0 app that installed the MSCOMM32.ocx control worked fine under Vista. I will report back when I figure out what I am missing under my new C# .NET 2.0 app installer. Curious... -Ed

The mscomm32.ocx control does work under Vista as I have used it. The page below includes mscomm32.ocx under the section "Tested and Not Shipping In Windows Vista". It *does* work. http://msdn2.microsoft.com/en-us/vbasic/ms788708.aspx The problem is most likely a dependency issue. Open a command prompt and go to C:\windows\system32\ and run "regsvr32 mscomm32.ocx". If DllRegisterServer fails it is likely a dependency issue. I have reproduced the problem in registering on a clean Vista VM. I will figure out what I am missing and report back my findings. -Ed