I am using a windows 7 64bit, Ms security essential, and i installed PSO2 at root directory of D drive (Consider my backup drive). What i have done so far:

1. Allow pso2 at firewall
2. Close real time protection of ms security essential
3. Delete gameguard folder in PSO2 folder
4. Update my graphic driver
5. Start game from pso2 tweaker

All the action above doesn't solve my problem, anyone have this issue before? Please help me~ thanks