FF 3.6.2 / MacOS 10.6.2 / JSON.parse error

[RM]

I've setup Toby's minimal server from http://people.mozilla.org/~telliott/weave_minimal.tgz

I have FF 3.6.2 and tried Weave 1.1 and 1.2b2, but the Activity Log
always ends with a Service.Main JSON.parse exception. This occurs on
two machines (same FF, same MacOS). I've tried removing all other
addons, no success. (Weave appears to be communicating with the
server just fine.)

http://pastebin.org/126984

Any advice? Thanks!