Thanks Loewchen, after reading all the other threads about bots "not working" i figured out, that i have to many ghosts builds not in range of any roboport.
After placing roboports in range of my ghosts all bots started to go on as usual.

So I have a suggestion for the developer:
Implement a ghost ...

I try to rework my factory and have many concrete (and other stuff) to be removed.
My bots started to remove the first "half" of concrete but then stopped and don't deconstruct anything.
Some of my deconstruction orders are for sure more than 3-5 ingame hours.
I just have 1 big network for my ...

I missclicked some time and the game crashed while using this bar:
http://cyberkeks.net/Factorio/FactorioBar.PNG

http://cyberkeks.net/Factorio/factorio-current_old.log

I can reproduce this:
http://cyberkeks.net/Factorio/The_result.PNG
http://cyberkeks.net/Factorio/factorio-current.log ...

Confirmed. Bug fixed in latest (experimental) version.

Reproducable. Just mark that pipe (left side of the base) and wait ~5 minutes.

I was also able to reproduce the error.
During my savegame I just concreted a lot and worked on my power plant on the side.

When I went with the mouse over a not yet built heat pipe the crash came (see screenshot).

Downloadlink: http://cyberkeks.net/Factorio/_autosave2.zip