I realized that when fighting twice in a row in PVP in less than 2 minutes = CVE. So I'm alternating 1 fight in PVP and 1 in PVE. I don't have more problems. Sorry for my english.
I have been completing my PVP all at once, all 5 in more or less than 2 min. I don't get the validation error all the time. It just pops up sometimes, less often
OH and btw, completing tasks like " defeat carnage in spec op mission 2" wont be completed if done using the autowin cheat. This is just a reminder not to waste those ISO by playing that mission once again to complete the task