Virus generates sounds - how to disinfect?
I have most likely a virus in my computer, which is playing short sounds (noise) for second or two at random times. When the problem is "on" the noises repeat every 5-10 minutes, and a random 1-2 second sound is played from speakers. Then it might disappear for a day or two, and then occur again. In addition when the problem is "on", the Windows volume mixer application detects a constant signal from Firefox browser, but nothing is being played from browser , or any other application, and no sound is heard, and no signal is detected in main speakers channel. But when the noise occurs, the signal is also shown in the main speakers channel, and it can definitely be heard.
So far I have started Windows 10 in Safe mode with networking, installed Malwarebytes, Kaspersky and Windows malicious software removal applications, but none of those detected anything. After that I had problems uninstalling Malwarebytes, but was finally able to do it by rebooting to safe mode. The sound problem has not disappeared, it occurs randomly.
I'm looking for instructions / next steps on how to disinfect the computer. I'm running F-Secure SAFE.