For anyone experiencing Error 72 delete everything inside your gamegaurd folder. For me it is located at C:\Ntreev\Grand Chase\GameGuard but it might be different for you. Then start GrandChase normally and it will re download the GG files.
Remember to start the Sandboxie grand Chase first.
As for the Virus Scan, the link I posted for Sandboxie came straight from the official Sandboxie website, so I don't think a virus scan is needed. You can go to Sandboxie.com or Google Sandboxie and check the download link on the site for yourself.
If you need further proof that this works I can upload a youtube video showing you step by step. There are only 2 steps so the video is really just for proof.
Remember to start the Sandboxie grand Chase first.
As for the Virus Scan, the link I posted for Sandboxie came straight from the official Sandboxie website, so I don't think a virus scan is needed. You can go to Sandboxie.com or Google Sandboxie and check the download link on the site for yourself.
If you need further proof that this works I can upload a youtube video showing you step by step. There are only 2 steps so the video is really just for proof.