SharePoint 2010 - 404 Not found Error?

After a migration from 2007, and navigating to the default.aspx page I am getting a 404 Not Found error.

I am unable to dete开发者_开发问答rmine where this is coming from. I have looked in the event viewer as well as the ULS logs but cannot isolate the cause of this problem.

Any ideas on how to locate this problem? thx

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Check out the system event logs.