Yes, it flushs the cache and some instances might be in use. That's why the warning is logged.
I have the same problem, but using the Commit Option C...
The thing is that I need that option to keep our EntityBeans up-to-date with DataBase because of other external processes that insert data into it.-
But when these warning msgs appear, it takes a lot of time to have the JBoss reply: It makes it slower...is there anything we can do to avoid this situation ?