If you unplugged your soundcard, you'll have to go back into Options>Audio>try MME or WDM, assuming you were using ASIO for soundcard. Anytime you switch you have make sure playback device and Audio options are for what you are actually playing back through. Check your outputs in one of your tracks, what does it say?
HP Pavilion dv6 Intel Duo Core 2 2.20GHz T6600, Windows 7 x 64, Guitar tracks Pro 4, SonarX1dEXP,SonarX2Prod. 8.5.3, Focusrite Saffire 6 USB, JBL monitors, Alesis SR-16, Guitar Rig 4 Pro, PRS SE, Epiphone Les Paul Custom, Cort SJ-10 ,Steven Slate 3.5, Akai MPK25, Glyph GT 050Q (500GB)RP1000
http://soundcloud.com/mar...ayin-around-mix1