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I've been running Ubuntu for about 4 years now, and I'm having a problem with 12.04
Every once in a while the computer will slow almost to a stop, interrupting any playing audio/video, and essentially becomes unusable for a minute or more. I keep checking the system monitor, but it shows me using less than half of my RAM. I've got swappiness on 10, the suggested value for my 4GB RAM. Dell Inspiron 1545, Intel Dual Core 2.1GHz.
I've checked out some of the other threads for help, but nothing seems to work.