Error: detecting hexadecimal error value 0x00 is an invalid character. Line 1, position 1

Today I use Trados Studo (2014) to translate a word 2007 file and save and exit the Studio with half of the contents being translated. Several hours later I reopen the saved XLIFF file, but the Studio reports error as somewhat "detecting hexadecimal error value 0x00 is an invalid character. Line 1, position 1" (as I am using Studio Chinese version, so this message is just an essential translation). After I click the OK button, the file fails to be opened. Is there be any solution to address this problem? Highly appreciated for any constructive suggestion.