Run a Search for Files and Folders, and search for anything greater than 2000K in size. You may have some big nasty unknowns out there. Otherwise you might have a virus or hit a limit on the drive's error recovery capacity. Do you get any messages on boot up such as "Imminent disk failure..."?

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1985 380SE Blue/Blue - 230,000 miles
2012 Subaru Forester 5-speed
2005 Toyota Sienna
2004 Chrysler Sebring convertible
1999 Toyota Tacoma