Yes you understand correctly. When you compile the plugin with VC++ Express SP1, it will not run on systems that don't have VC++ (SP1 or not) installed. If you compile with VC++ without SP1, it will work on every system.

This probably doesn't happen for every kind of program compiled with VC++ Express, or this would have been solved long ago. However, it might be that gamestudio plugins (which must have a certain compiler/linker configuration) all suffer from this problem.

More testing is required to see if a simple plugin (the sample dll that comes with the SDK for example) also has this problem when compiled with VC++ SP1.. If it does, this should make it into some FAQ.

BTW, could you confirm that it now works for you on a system without VC++ installed?