Hi
Today you are faced with a riddle. During the game, I was thrown to the desktop more and more often without warning, from a certain point (act III) I cannot exit to the menu from the game level (the"save and exit option is treated too literally" 
). Currently, I can’t even run an online game because it won’t let me into Act V. (Hope it’s not because of naming my assasin Karen 
) Maybe someone will come up with a solution.
Pc:
Intel I7 4770
16GB ddr3
Geforce GTX 1060 6 GB
Motherboard- Msi b85m-e33
All drivers are up-to-date, the game has been reinstalled several times
I faced a similar issue when wp’ing to act 5 then the game crashed
Upon entering the game again it just crash over and over.
Im my system log it said that d2r.exe used apox 8GB memory so it shut down.
If you start a new game on another difficulty then youll start in act 1
Another thing that might help is restarting your PC - that worked for me.
Havent had this issue since.
i have random crashes too.
Act 5, Act 4, cow-level… doesnt care, its happening randomly everywhere.
AMD Ryzen 9 5900X
RTX 3070 ti
32gb RAM 3000mhz
Samsung 870 evo plus SSD
Windows 10 latest
Dunno whether its connected to other software.
Thank you for guiding me to RAM Consumption. I solved the problem and I am happy to share with others. 
The whole problem with the D2R is in the memory usage (that’s why it crashes to the desktop) Just increase the virtual memory, in my case I increased to 10 gb and everything works (act V and no desktop crashes).
I hope it will help you too