I have a pretty tried and true application I continue to develop with VB6. I have been developing the app on Windows XP machine and it has been running successfully on our users machines, both in Windows XP and Windows 7. Now, I have a new Windows 7 machine which I must use for development. All seemed to go OK with install of VB6 (SP6) and a few older third party controls (ActiveResize and RoboPrint) I continue to use. I needed to make one change to the application, which I did on the new machine and compiled, then deployed to a Windows XP and a Windows 7 machine. It worked fine on Win7. It fails before really even starting on the XP machine with "Runtime 91 Object variable or with block variable not set". I tried adding some extra debugging MsgBoxs to the startup form, and it doesn't even reach that point. Further, I am unable to access Project-References as I'm receiving "Error Accessing the System Registry" - this may be unrelated but wanted to mention. I also had some old stuff using Crystal Reports, and I uninstalled all of that and removed it from the project, as I read this "Error Accessing the System Registry" might be related to that. This didn't help my Runtime Error or the Registry Error. I then tried uninstalling VB and reinstalling, running as Administrator, but the re-compiled EXE still gives the Runtime 91 error on startup. I also tried setting VB Compatibility to Windows XP SP2 (and then 3) but this didn't seem to help either. I'm not sure how to debug this error further. Any ideas?