Bizarre !
I've had no issues at all for around 2 weeks. 
You're using firefox aren't you Nino? I find there are very few probs with it, every now and then I find a thread with an unread post not coming up in the "Show unread posts..." but it's pretty rare. Not sure if IE has more probs??
I use Firefox, and I've had no problems for a while. All defaults are set in the options..
