Ratkill,
That tends to happen if you use a shared buffer file between multiple clients. The best way to avoid it (if this is really what's causing your problem) is to set your clients to use remote buffers rather than shared. That way you can still keep the fetch/flush data on one machine but the clients will store there own smaller buffers locally and this should stop you getting buffer locked.
Of course if this isn't what you're doing, just ignore me
