I think have a pretty good number on virtual memory. Initial Size(MB): 3000 Maximum size (MB): 20000

no is not enough
raise it to 48.000 it should solve your problem
switch your mining to a linux distribution cause your cards of 4gb will mine much longer on linux than on windows, and linux is more stable
Linux more stable? Why? Explain!!!!!!!!!!!!!!!
I think you are wrong, setup win10 in the right way, it is also stable. Running my Rigs on win10 over 3 or 4 months without reboot is no problem.