With the limited detail in your post my bet is this should stop it.
Over the past 2 days, I have been getting the following dialog appear more than usual, & more often now in quick succession:
"A username and password are being requested by http://www.google-analytics.com. The site says: [brand name of my router]"... Each time it is requested by a different organisation/entity.
Can someone kindly tell me what it actually is & why I am getting this? Is there some way to turn it off? Most importantly, should I be very worried...??