Due to some complications regarding the license problem, here is the solution. Cheesy
After done installing OrCAD Release 10.5, there should have a line in the environment variables:
Variable name: LM_LICENSE_FILE
Variable value: (something\cadopia.dat)

Just change that Variable value to:
(something\orcad_v105.dat)

The file "orcad_v105.dat" can be found in CD1\Crack folder. Just put that file in any place of the hardisk, and point the Variable value to the file.
For example, I put the "orcad_v105.dat" in C:\Temp, so I should right click "My Computer", select Properties->Advanced->Environment Variables. In either system variables or user variables section, find the "Variable name = LM_LICENSE_FILE", then change the corresponding "Variable value = C:\Temp\orcad_V105.dat".