I Hit the search button on BBF...
punched in: "LOST BROWSER"
this thread came up and a few others including this one:
http://www.blackberryforums.com/show...t=lost+browser
Try re-registering on the network.
homescreen-options-host routing table-(hit trackwheel) and "Register now".
If that doesn't work, log into your webclient/internet service and re-send the service books and repeat.
If that doesn't work, hit alt-trackwheel and show-all.
If that doesn't work, re-post.