This just started yesterday and i'm not sure why, but when I click on a link in gmail or google talk my screen dims but the link isn't opened in the browser.
Sounds like it lost the default setting for opening links. Try rotating the screen to portrait and see if you get the prompt to choose which app to use.
I had this happen to me after I installed opera and another browser. It had lost the default setting for opening links. After I rebooted, the next Time I hit a link it asked me which app to use to open it, and the pop-up also had the checkbox to set it as the default app for opening links.
Thanks for the tips, they both helped! I had installed the Dolphin Browser for Tablets, when I uninstalled it the problem went away. When I re-installed it the problem came back. I did the rotate thing and the option to select came back. I normally keep the screen in landscape mode and don't even have the rotate on.