Welcome to Seven Forums LJBAY60. When this happens, do you get a Not responding message in the top of the browser window? Are you able to close the window, or use the back button, or must you close the browser? Which browser are you currently using? If this is a repeatable problem with certain sites, Debbie's suggestion above of an alternative browser may help track this down. If it is random, it will be harder to do.
You can also try using IE (No add-ons) and see if the problem persists (assuming you are using IE currently).
Start> In search box type Internet explorer> Click on Internet explorer (No add-ons) in results above.
If problem persists, you can also try a clean start to see if something is conflicting Troubleshoot Application Conflicts by Performing a Clean Startup