[ubuntu] How to check disk for errors?

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http://ubuntuforums.org – My Ubuntu just freezes up and then sometimes goes into a command line-like screen with a bunch of lines. I have to restart my computer by holding my power button until it shuts down and then I restart it. As I'm typing this thread, it's freezing. What can be the problem? Is there a tool to check for bad sectors on my drive? Like in Windows how they have check disk? What should I do? Attached Images 471278_412693265411030_100000110792878_1782365_800701925_o.jpg (179.5 KB) (Hardware)