First, you should check if you can stabilize the memory on Linux or Windows, my suggestion is to test y-cruncher or TM5 with profile 1usmus_v3.
as you say this problem does not happen on Windows, it could be a problem with a Linux driver and maybe it affects other distributions, however, Ubuntu may have problems that do not happen on others, in the same way that some less popular distributions also depend of what they are packing.