A CD quality WAV file is 16-bit, 44KHz. This is a long shot, but try checking the properties of the FLAC source on the second album. Depending on the how it was encoded they may be 24-bit, 48KHz. If this is the case, you may need to force a 16-bit output WAV from Foobar when you transcode it. Another thing would be to try a thumb drive. Good luck!
'13 EBII 335i M-Sport (on the way)