Hi- I'm not an expert but maybe this helps...
1) you don't have to func_wall every wall... normal objects are solid and can not be seen through
2) sometimes running via hammer can be tricksy- try running the program from the mod, after compiling with hammer
3) It may be possible to put too much stuff in a map- certainly if it is a func_wall... I think these don't get "vis"d so the computer tries to display them all the time, then masking them with nearer objects. I hope someone with more knowledge checks this but basically I think you want more normal objects and less func_walls.
4) If you have an inch-by-inch replica of your house you will have to remove quite a lot of detail. Small objects break up how the game displays surfaces they're in contact with... otherwise you may get more probs from memory space.
5) have you checked around for error pages and tuts that might help?