I'm having the same trouble and wondering if you have any other ideas.
I took your advice and am running the latest pg_foundry (2.0.0) ppm as well as latest Pg (8.3.3) and Activestate 5.8.x (522).
But I'm still having the issue. I don't have a better trace than the others, but I think I do know the type of behavior that is causing the problem. I've been running various load and stress tests, and it has only occurred when a lot of clients have killed the connections prematurely. The only evidence of this is in the pg log.