Hi. Sounds the bug I just reported. In my case I found out that it was related to AO - if AO is used the renderer won't stop, but if no AO is used everything works as expected. So far I and others have seen this in v1.2.1 and newer (daily builds). But since you are using v1.1 it would be interesting to know if our problems are related.
So... do you use AO in any material? And if so, what happens if you remove/disables it?
Regards