Neil,
All the function calls look correct based on the MSDN documentation. Is there a pattern with respect to OSes in question. You state that the machines are older but not what operating systems are being used.

Can you place code in the Error event of the form to suspend it on error? That way you may be able to determine where the actual problem is.

>Thanx Larry,
>The date of Advapi32.Dll is 05/11/98. But I have some systems running the component that have that date. How about other functions I saw in the Mailmanager's method: RegQueryValueEx, RegCloseKey. The actual error is invlaid number of parameters. Is it possible that some versions of the dll was not as forgiving when it came to passing parameters?
>
>The exact code lifted from the methos is:
>DECLARE Integer RegOpenKeyEx IN Win32API Integer nKey, String @cSubKey, Integer nReserved, Integer nAccessMask, Integer @nResult
>DECLARE Integer RegQueryValueEx IN Win32API Integer nKey, String cValueName, Integer nReserved, Integer @nType, String @cBuffer, Integer @nBufferSize
>DECLARE Integer RegCloseKey IN Win32API Integer nKey
>
>How do these calls look to you?
>Neil
>