Akuramini,

First off, please note that we have not confirmed compatibility on any Radeon HD cards newer than the 6800 series, as detailed on the Official PlayOnline website, so we’re not able to guarantee perfect performance on your card. That being said, if your hardware itself is locking up entirely, to the extent that you need to actually restart your computer, that’s more indicative of a hardware issue, than anything software related. FINAL FANTASY XI may be triggering this failure, but it’s still a hardware failure, be it the power supply, motherboard, video card, or any other integral part of your hardware. Since that is the case, we can only recommend proceeding with hardware troubleshooting, contacting the hardware manufacturers for support.