Threads all showing "Read"

[DorsetTangler]

Why is it that today, every sub forum I visit on here and every thread within that forum is showing as read? (on my machine light green text as opposed to bold, dark green text for unread)
Even threads I've started that have had new replies arent showing me there are unread posts in it.

Really annoying it is

This is the only site where I notice this happen.

Is there a cure?

Thanks.

 

[sumtime]

Go fishing.