Hello!
I am having a problem with my windows 8.1 machine. The hardware is a stock Dell Precision T5400 with a single Xeon processor and an Asus graphics card. When I boot up my machine, the audio icon in the bottom right hand corner (ie the little speaker) has a red 'x' symbol beside it. When I hover my curser over it, it says 'No speakers or headphones are plugged in'. However, I have headphones plugged into jack on the front on the unit. When I click on the icon it brings up the Audio trouble shooting window. After about 5 seconds the window changes saying 'Troubleshooting couldn't identify the problem.' So I closed the trouble shooter. I then went into the Device Manager and checked to see if my audio driver was recognized, it wasn't. The weird part of this is that the audio was functioning normally up until a few days ago. I don't know what to do next.