The Stratum message is a part of NTP. Why we get it when the clock tries to use time.windows.com is anyones guess, but I think that that timeserver is probably over-run and the stratum message happens as a punt, or maybe because of some other network problem.
NTP has a general worldwide problem with too many people trying to use top level servers too often
Read about it HEREThe long and the short of it is to set your clock to use pool.ntp.org. Your time will be almost as good or maybe even better than with the other servers.
I've been using us.pool.ntp.org with good results and I have pretty fast ping times there as well.
...and I don't get any stratum messages in my logs
bullshark2