I have 2 problems which have just started occuring when I try to access websites, 400 Bad Request messages and pop up window asking for a user name and password for normally open sites. An example of the Bad Request message occurs when I go to the Guardian webpage https://www.theguardian.com/travel/2012/jul/11/top-10-pembrokeshire-walks which displays normally but when I try to follow one of the links which should take me to National Trust pages I get the 400 Bad Request message. I have used this website before with no problem but this has started occuring on this and other sites over the last week. I also get the message when I try to go to http://www.nationaltrust.org.uk/main/ from the bookmark I have used for many years. The other problem occurs when I type www.nationaltrust.org.uk, I get a pop up window which says Authentication required - Mozilla Firefox http://www.nationaltrust.org.uk is requesting your user name and password. The site says: DSL-3782 Usaer name Password. Cancelling the pop up causes 401 Unauthorised message If I give it any usename and pass word it comes back the the blank pop up again except when I enter my DSL-3782 router username and passwood which gives routers Internet status page with no errors or messages. I have tried clearing caches etc. with no effect. These problems also occur on some other websites and on my laptop. Has anyone had these problems? What is the cure?