ONe thing. Never had this happen on Yahoo or Yahoo mail but have on other sites.
FIrst: SHut down and turn back on the computer..
NORTON has a "Nanny Gate" one of the RV parks I visit has Norton nanny gate installed due to some jerk downloading a prohibited download (Copyright I suspect) so instead of invoking Post office Rules the park put in a nanny gate (Stupid.. The Park has ZERO liability if someone downloads counterband unless the someone is park mangement)
THe blasted Nanny Gate won't let me access PCH.COm and what is worse also a felony in this state, it installs something on my Phone or Chromebook that redirects me t the "Prohibited" page EVEN IF I SWITCH TO T-MOBILE as my ISP (aay from the nanny gate) I told you the park was stupid, THEY INCURE LIABILITY if I were to sue them for that.
Turning the devices off and back on fixes it (Thankfully it's only in RAM not in storage).
THe other thing is clear all cookies and caches Sometimes that's where the problem lies.. Of course you now have to log back into everything but.. Well I have an assistat for that.