First of all, I think we'd need more info to try and help you.

Does this occur on all songs you try or just one specific song? If it's one specific song it might have been corrupted somehow and you'd need to re-enter it from scratch.

Does it occur with midi only songs? If midi only songs work you may need to defrag your hard drive as RealTracks need to create large temporary files with quick access.

Have you added any background processes recently such as a new anti-virus program or wireless networking? These processes could interfere with BiaB.

BiaB 2013 b366, RB 2013 b4, WinXP Pro SP3, Toshiba M70, 1.8GHz 2GB RAM 100GB HD. Focusrite Saffire 6 USB, Ketron SD2.BiaB Wiki