First off, those error codes only mean something to Adobe engineers, not to us mere mortals - send off the log file it creates to them at firstname.lastname@example.org just to keep them informed. Next, what's going on when this occurs? Is it happening when you start up FM (what version btw?) When you start a particular fm doc or book? Did it use to work? If so, what changed? Lot's of questions need answering to help troubleshoot an error message.