Thanks David,

I have my users install DCOM98 as the first step of the installation process. I got one user going by reformatting, and reinstalling everything. (re-installing wasn't enough) After my post I recalled that they also got C..5 when running my update.exe, which just copies some files so I know the REGFN() isn't causing it. I think I will go to directly calling the API function and see if my other problems go away. Thanks again.

Marcus.

>Marcus,
>
>The app startup crashes are usually more related to the lack of the current DCOM installed on the machines. Check the FAQ here I think Ed Rauh posted an article on solving it.
>
>You don't need REGFN() to work with the windows API any longer. You can DECLARE the function and call it directly:
>
>declare integer FindWindow in win32api ;
> string lpClassName, ; && pointer to class name
> string lpWindowName && pointer to window name
>
>lnHwnd = FindWindow( .null., "Visual FoxPro 6.0" )
>
>
>>I've been using the following Foxtools function to check for other instances of my app - GetWind=RegFn('FindWindow','CC','I') &®ister function. I have a few customers who get C0000005 or Illegal operation errors as soon as they start my exe. I've also noticed that I occasionally get 'Invalid API call' when running my code in development mode, and I am now wondering if these issues are related. Anyone have any experience with this? It started happening after we went from VFP3 to VFP6. TIA