In order to fix this error please follow the following steps :
1 : Run the ForsakenRO patcher
2 : If you're already patched up delete your fpatch.inf and run the patcher.
In case this does not work do the following :
1: Download the small patch(80mb) from the website.
2: Install this patch into your RO folder.
3: Run the patcher and let it patch.
4: Press start when it's done and have fun playing.
Regards,
Ryuk