The sound on my computer has been acting rather strange for nearly a year.

Everything worked and sound came through the speakers when we first got the computer, but one day it decided to stop working (nothing had been changed or reformatted on the computer). Sound still comes through headphones if plugged into the tower, but never through speakers. We bought new speakers, everything is plugged in properly and nothing is muted. The driver is declared as working properly in the device manager. However, the "Realtek Audio Manager" never pops when clicked in the control panel like it does on my other computer which has the identical version. I'm lead to believe the program is faulty.

When I run "dxdiag" it says: "RtkHDAud.sys is not digitally signed". I have un-installed the program, and re-installed it, and partially through the installation, it says that the program is not digitally signed by Microsoft and that it is unsafe to continue with the installation. I click "continue" anyways, reboot the computer, and the re-installation has made no difference.

I have also tried to update the driver, but windows states that it is the most recent version.

So my question is: Why is the audio driver considered "not signed" and how can I fix this problem?

you could buy a PCI Sound Card for you computer .