We made a lot of tests to find out the cause, and here the results:
1. I can reproduce this error with 100% success. And I'm ready to give you any logs or other info to fix this issue.
2. It's not related to my software or hardware because the same issue happens to all people from our community. And we did a lot of special tests with 6-8 people in many multiplayer sessions and crash happens for all of them.
3. The crash happens on clients, on host (non dedicated) and on dedicated server. We tried different scenarios.
4. The crash is related to SMD Sahrani A3 island, but before 1.50 it worked perfect.
5. I tried to remove all buildings, roads, vegetations, rocks and all other objects from this island. It doesn't help. I had only terrain with ground texture and nothing else but game was crashed anyway.
6. It looks like error happens when game is trying to release something from memory. Because it can happen when you switch to another island, or flying through some area, or when you reconnect to the same session (go to lobby and then back to game).
7. The error messages are varied. Some times it says 'memory could not be written'. Some times it says 'memory could not be read'. Some times it crashes without any message. But always it related with access to low memory addresses.
8. I tried the latest dev build (2015-10-07) and it doesn't help.
9. I tried different memory allocators and different strtup options it doesn't help.
10. I tried legacy 1.50 build and the error is already there. I can't try legacy 1.48 build because it's not accessible.