But there's so little detail, where to begin or end?
1. Use the GOOGLE DNS instead. Don't know how? Google "How to use the Google DNS?"
2. Antivirus web browser addons. Sorry but I find them too buggy. Test without those.
This is really frustrating and it has got worse in the last week or so. It is only happening on the one device connected to my wifi, my windows 7 laptop. Every few internet page the message comes up "Cannot be displayed". It happens on Chrome, Explorer and Firefox. I have to refresh 6 or 7 times before the page is finally loaded. I have checked the all the proxy settings and everything looks fine, even checked the drivers, everything up to date. Every other laptop/phone in the house is fine. Any help appreciated!!