freeze on loading map!

Hi everyone, I’m working on a simple project with a friend of mine, so we need to swap it between us using an external HDD.
During the last week he worked a little bit on the level design, and today he gave back the project to me.
Now I’m trying to open it, but when it loads the map, my computer completely stops working: I really can do anything but restart it.

This is the CPU and memory usage during the loading of the map

Could it be a ram overflow? I have 8 Gb on my pc, and my friend has 16 Gb, as a matter of fact he always opened the project correctly.
But I really can’t believe that the map is so heavy… The landscape is quite little, He just added some foliage (kite demo nature pack) and some assets from infinity blade content…

RAM is definitely going to be a problem if you are running out. You said that you have to restart your computer, what about killing the UE4 process in task manager? Does that not work?

I’ve tried that but task manager didn’t open, and same for exiting from Unreal with alt+f4 or switching to desktop with alt+tab… that wasn’t just a crash of Unreal, the computer was totally freezed.
And it happens only when I try to open that map (there aren’t other maps in the project), but the project opens correctly.

The strange fact is that on this pc I’ve correctly opened and loaded some maps a lot more heavy, like the kite demo one, elemental demo one and landscape mountains…

Yesterday my friend tried to download our project from the ext HDD (the same file that freezed my pc) and opened it without any problem (loading the map took just 2 or 3 Gb of memory to him). We deleted some useless assets from the viewport and hide foliage and particles, and re-uploaded it on the hdd. Then, at home, I tried again to open it, leaving the pc loading the map for about half an hour, with success. Now it takes a couple of minutes to load the map and save it, but I’m finally able to work on it.
Anyway, I can’t consider the problem as solved. Has there anyone an idea for what appened?