That message often comes up with MFC-based Pocket PC apps on H/PC 2000 devices because the H/PC 2000 versions of mfcce300.dll and olece300.dll are not the same as the Pocket PC versions that the app needs. It also occasionally comes up when the wrong aygshell.dll file is being used. Both are relatively easy to remedy.
(Of course, there are are other possible reasons too, not all of which are as easy to solve.
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