I'm using Terragen 2 1.9.04.1 Deep and keep seeing this anomaly when rendering. When I inspect the Terragen 2 process in Activity Monitor, the Shared Memory Size jumps every now and then to 16,777,216.00 TB. I assume this is the 16 Exabyte limit addressable by 64-bit processors. The application seems to hang when this happens. I'm running Mac OS 10.5.1 on a PPC Macintosh. I'm sure that addressing this bug will help performance.