Problem with C# project deployment with Mappoint 2006

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I have two weird problems with my C3 application with a Mappoint2006 (North
America) windows form control. It compiles fine with vs2005 and it runs on my
PC (win xp) as well. But whenever I tried to migrate the application to a
different system:
(1) For PCs (all have MS MP 2006 NA installed) also in North America, the
application runs but fails at the first mappoint function call of
"MapPoint.GetLo cation()", complaining "Unable to cast COM object of type
"System.__ComOb ject' to interface type 'MapPoint.Locat ion'
(2) For PCs in Europe (with MP2006 EUrope installed), double clicking the
application exe doesn't even do anything!!!
Can anyone help here?

Thanks a million!