The Nexus is at 400?

This explains why it doesn't run on my system. I don't know what takes so much memory with my setup, but even after closing firewall and antivir still over 100 MB are in use... so I end up with about 400MB free ram, which doesn't seem to be enough.

I also had a problem with max entities exceeded. The limit is increased with increasing nexus, but it can also be raised manually: max_entities (I guess this it what you tried first?)

Haven't tried publishing, as I always use resource, but maybe this indeed is an engine problem.