Hello Ihnil Kim,
Sorry for getting late on reply.
Are you still seeing this issue?
Couple of questions,
We saw this type of issue generally happens when your installation is not correct.
Which version of Dynamo are you using?
Which was the previous version of Dynamo on your system?
Can you try this, uninstall Dynamo delete its directory fro C:\Program Files\Dynamo 07
Ans then re-install Dynamo.
I know this is not a proper solution to your problem, but I am trying to understand what went wrong.