Hanging renders

The last bug I'm tackling is that sometimes the WikiTool render queue hangs.
It might also be other queues, but it's Wiki I've been working on. I'm not
seeing any errors in Events, or error.log, but this is showing up in
etc.log: 

mesh(_acquire): waiting for lock at Tue Jul 13 16:49:24 2004 

I *suspect* I've either got a single thread trying to acquire the lock
twice, or two threads deadlocking, or one thread dying whilst it has the
lock. Is there any infrastructure to help me resolve this? 

Regards,
Garth.