Why does Ubuntu keep freezing when I install updates or new software?

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http://askubuntu.com – I used Wubi to install Ubuntu 12.04.1 LTS today. Whenever I install updates or new software the system freezes for several minutes. Programs "turn gray", everything is unresponsive except for the mouse and the sidebar. There is no action from the hard drive either so it seems like nothing is happening during that time. Then all of a sudden you hear the hard disk starting to work and the programs are usable again, for about 20-40 seconds, then it freezes again. Installing software or updates takes forever because of those pauses and I can't even use firefox while installing. There has to be (HowTos)