I am not sure if the validate problem has been fixed or not but of the work units that I have returned during the last few days most of my validate errors have been with Linux.
Windows 5 validate errors from 39 results = 12.82%
Linux 17 validate errors from 46 results = 36.96%
Plus I wont get credit for a number of these work units as they get sent out to others on 1 hour preference run time against my 6 hours and often then validate. When the same work unit will fail at the longer run times.