Windows 7 laptop died, was running a circa 2010 version of Thunderbird. Purchased new windows 8 machine, downloaded and installed newest version of Thunderbird without problems. Copied abook.mab and history.mab from my backup drive to the appropriate folder and get this error message: "Unable to load address book file history.mab. It may be read-only, or locked by another application. Please try again later." Can not get to the address book.