Hi folksSome of you might also have encountered the nasty issue of Corel PhotoPaint (CorelPP.exe) to open a new instance of PhotoPaint for every CPT file being double-clicked for opening. After twiddling around and searching the web, I finally found out that CorelPP.exe is case-sensitive for DDE commands. As such, using the DDE argument 'Open("%1")' won't do anything.The solution for Corel PhotoPaint X4 (CorelPP.exe) is:Application used:"C:\Tools\Office\Corel\PROGRAMS\CORELPP.EXE" -DDE "%1"DDE Message:[open("%1")]Application:CORELPPDDE Application not Running:<empty>Topic:SystemCorresponding registry file:-----------------------------------------Windows Registry Editor Version 5.00[HKEY_CLASSES_ROOT\CorelPHOTOPAINT.Image.14\shell\Open][HKEY_CLASSES_ROOT\CorelPHOTOPAINT.Image.14\shell\Open\command]@="\"C:\\Tools\\Office\\Corel\\PROGRAMS\\CORELPP.EXE\" -DDE \"%1\""[HKEY_CLASSES_ROOT\CorelPHOTOPAINT.Image.14\shell\Open\ddeexec]@="[open(\"%1\")]"[HKEY_CLASSES_ROOT\CorelPHOTOPAINT.Image.14\shell\Open\ddeexec\Application]@="CORELPP"[HKEY_CLASSES_ROOT\CorelPHOTOPAINT.Image.14\shell\Open\ddeexec\Topic]@="System"