To resolve the CWinFileException error when creating a client package:

1. Stop the Officescan Master Service.
2. Go to the $OSCE server installation folder\Pccsrv\Pccnt\Common folder.
3. Create a backup copy of the DWIOTrapNT.dll_invalid file. You can copy it and then paste it to a temporary folder. 
4. Rename DWIOTrapNT.dll_invalid in the $OSCE server installation folder\Pccsrv\Pccnt\Common folder to "DWIOTrapNT.dll".
5. Start the Officescan Master Service.
6. Create a client package.

The CWinFileException error should no longer appear.

If the issue persists, please contact Trend Micro Technical Support.