It didn't happen overnight! It was a long slow decline. Read carefully:
http://www.google.com/search?q=why+roman+empire+fell&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a
WHY DID THE ROMAN EMPIRE FELL
3 answers
Some claim that the Roman Empire didn't actually fall -- but moved the capital to Constantinople. Its legacy continued on in the Roman Catholic hierarchy and the Holy Roman Empire.
These sites discuss many of theories about the fall of the Roman Empire. Note that the first site has listed some admittedly silly reasons.
http://www.csun.edu/~hcfll004/fallrome.html
http://ancienthistory.about.com/od/fallofrome/Rome_The_Decline_and_Fall_of_Rome_and_the_Fall_of_the_Roman_Empire.htm
These sites discuss many of theories about the fall of the Roman Empire. Note that the first site has listed some admittedly silly reasons.
http://www.csun.edu/~hcfll004/fallrome.html
http://ancienthistory.about.com/od/fallofrome/Rome_The_Decline_and_Fall_of_Rome_and_the_Fall_of_the_Roman_Empire.htm
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