Browser Fails to load pages after a few minutes. ubuntu 12.04 x64

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http://ubuntuforums.org – hello. I'm using ubuntu 12.04 x64 on a lenovo s10-3 netbook (specs http://www.cnet.com/laptops/lenovo-i...-33953705.html) and when I use chromium or firefox for a little bit it just stops loading pages and gives the sad face with "this page cannot be displayed". the only way I can get it to work again is to reboot. I've tired switching from unity 2D to lubuntu netbook desktop and the same thing happens. I cleared the cache with ctrl+alt+delete and that didn't solve the problem. I'm still learning the terminal so I'm not sure how to open chromium with the terminal running. It would se (Hardware)