Hi, I`ve lost all sound coming out of my old faithful Dell running XP. I`m fairly clued up with XP and tried all the obvious volume solutions. SigmaTel audio is installed and driver is up to date. I was running a line to my amp via the front jack plug but all this does now is send a loud buzzing signal and the rear jack does nothing. I did `short out` my amp last week doing a repair on it, could this have sent power the wrong way and caused the problem? Any advice gratefully received, thanks.